perf(commons): remember derived values in the moved note cards

Audit follow-up. These renderers sit in scrolling feeds; each recomputed
event parses / string builds directly in the composable body instead of
caching them against the (immutable) event — the CLAUDE.md rule-#4 pattern.
The cards are already skippable (immutable event params + strong skipping),
so this is work redone per composition (each item scrolling into view), not
per frame; still worth removing. These patterns pre-existed in the Android
originals and were carried over faithfully — this cleans them up now that the
code is shared.

- RelayDiscoveryCard: the heaviest — 6 `joinToString` + a `.sorted()` ran in
  the body. Now each display string (network / relay-type / requirements /
  supported-NIPs / accepted-kinds / geohashes, the requirements lock flag, and
  the relay-URL displayUrl()) is `remember`ed off its parsed list; the row
  visibility checks still key off the original lists so behavior is identical.
- CalendarRsvpCard: `status` / `calendarEventAddress` / `freebusy` parses now
  `remember(event)` instead of re-scanning tags every composition.
- CalendarCollectionCard: `title()` and `calendarEventAddresses().size` (which
  allocated a whole List just to read size) now `remember(event)`.
- PodcastValueSplits: the `recipients.filter{}` + `totalSplit()` now
  `remember(value)`.

Behavior is unchanged (same keys, conditions, and outputs). Verified:
:commons:compileKotlinJvm + :amethyst:compileFdroidDebugKotlin pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gmrt3jwYPDJ38MJGJ6GaNr

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/ui/note/CalendarCollectionCard.kt

@@ -29,6 +29,7 @@ import androidx.compose.foundation.layout.size
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.text.font.FontWeight
@@ -46,6 +47,9 @@ import org.jetbrains.compose.resources.pluralStringResource
 /** Card for a NIP-52 calendar collection (kind 31924): title, description, and event count. */
 @Composable
 fun CalendarCollectionCard(event: CalendarEvent) {
+    val title = remember(event) { event.title() }
+    val eventCount = remember(event) { event.calendarEventAddresses().size }
+
     Column(MaterialTheme.colorScheme.replyModifier) {
         Row(
             modifier = Modifier.fillMaxWidth().padding(start = 10.dp, end = 10.dp, top = 10.dp),
@@ -59,7 +63,7 @@ fun CalendarCollectionCard(event: CalendarEvent) {
             )
             Spacer(modifier = Modifier.size(8.dp))
             Text(
-                text = event.title() ?: "—",
+                text = title ?: "—",
                 style = MaterialTheme.typography.titleMedium,
                 fontWeight = FontWeight.SemiBold,
                 maxLines = 2,
@@ -80,7 +84,6 @@ fun CalendarCollectionCard(event: CalendarEvent) {
         }
 
         Spacer(modifier = StdVertSpacer)
-        val eventCount = event.calendarEventAddresses().size
         Text(
             text = pluralStringResource(Res.plurals.calendar_collection_count, eventCount, eventCount),
             style = MaterialTheme.typography.labelMedium,

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/ui/note/CalendarRsvpCard.kt

@@ -29,6 +29,7 @@ import androidx.compose.foundation.layout.size
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
@@ -49,9 +50,9 @@ import org.jetbrains.compose.resources.stringResource
 /** Card for a NIP-52 calendar RSVP (kind 31925): the going/maybe/not-going status, note, and target. */
 @Composable
 fun CalendarRsvpCard(event: CalendarRSVPEvent) {
-    val status = event.status()
-    val targetAddress = event.calendarEventAddress()
-    val freebusy = event.freebusy()
+    val status = remember(event) { event.status() }
+    val targetAddress = remember(event) { event.calendarEventAddress() }
+    val freebusy = remember(event) { event.freebusy() }
 
     val statusLabel =
         when (status) {

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/ui/note/PodcastValueSplits.kt

@@ -31,6 +31,7 @@ import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
@@ -60,10 +61,10 @@ import org.jetbrains.compose.resources.stringResource
  */
 @Composable
 fun PodcastValueSplits(value: PodcastValue) {
-    val recipients = value.recipients.filter { it.split > 0 || it.address != null }
+    val recipients = remember(value) { value.recipients.filter { it.split > 0 || it.address != null } }
     if (recipients.isEmpty()) return
 
-    val total = value.totalSplit().takeIf { it > 0 } ?: recipients.size
+    val total = remember(value, recipients) { value.totalSplit().takeIf { it > 0 } ?: recipients.size }
 
     Column(
         modifier =

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/ui/note/RelayDiscoveryCard.kt

@@ -70,17 +70,24 @@ import org.jetbrains.compose.resources.stringResource
 @OptIn(ExperimentalLayoutApi::class)
 @Composable
 fun RelayDiscoveryCard(noteEvent: RelayDiscoveryEvent) {
-    val relayUrl = remember(noteEvent) { noteEvent.relay() }
+    val relayUrl = remember(noteEvent) { noteEvent.relay()?.displayUrl() }
     val rttOpen = remember(noteEvent) { noteEvent.rttOpen() }
     val rttRead = remember(noteEvent) { noteEvent.rttRead() }
     val rttWrite = remember(noteEvent) { noteEvent.rttWrite() }
     val networkTypes = remember(noteEvent) { noteEvent.networkTypes() }
+    val networkValue = remember(networkTypes) { networkTypes.joinToString { it.code } }
     val relayTypes = remember(noteEvent) { noteEvent.relayTypes() }
-    val supportedNips = remember(noteEvent) { noteEvent.supportedNips() }
+    val relayTypeValue = remember(relayTypes) { relayTypes.joinToString() }
     val requirements = remember(noteEvent) { noteEvent.requirements() }
+    val requirementsLocked = remember(requirements) { requirements.any { !it.negated } }
+    val requirementsValue = remember(requirements) { requirements.joinToString { req -> if (req.negated) "!${req.value}" else req.value } }
+    val supportedNips = remember(noteEvent) { noteEvent.supportedNips() }
+    val supportedNipsValue = remember(supportedNips) { supportedNips.sorted().joinToString() }
     val acceptedKinds = remember(noteEvent) { noteEvent.acceptedKinds() }
+    val acceptedKindsValue = remember(acceptedKinds) { acceptedKinds.joinToString { kind -> if (kind.negated) "!${kind.kind}" else "${kind.kind}" } }
     val topics = remember(noteEvent) { noteEvent.topics() }
     val geohashes = remember(noteEvent) { noteEvent.geohashes() }
+    val geohashesValue = remember(geohashes) { geohashes.joinToString() }
 
     Column(
         modifier = Modifier.fillMaxWidth(),
@@ -89,7 +96,7 @@ fun RelayDiscoveryCard(noteEvent: RelayDiscoveryEvent) {
         // Relay URL header
         if (relayUrl != null) {
             Text(
-                text = relayUrl.displayUrl(),
+                text = relayUrl,
                 style = MaterialTheme.typography.titleMedium,
                 fontWeight = FontWeight.Bold,
                 color = MaterialTheme.colorScheme.primary,
@@ -121,7 +128,7 @@ fun RelayDiscoveryCard(noteEvent: RelayDiscoveryEvent) {
             DiscoveryInfoRow(
                 icon = MaterialSymbols.Language,
                 label = stringResource(Res.string.relay_monitor_network),
-                value = networkTypes.joinToString { it.code },
+                value = networkValue,
             )
         }
 
@@ -130,19 +137,16 @@ fun RelayDiscoveryCard(noteEvent: RelayDiscoveryEvent) {
             DiscoveryInfoRow(
                 icon = MaterialSymbols.Dns,
                 label = stringResource(Res.string.relay_monitor_relay_type),
-                value = relayTypes.joinToString(),
+                value = relayTypeValue,
             )
         }
 
         // Requirements
         if (requirements.isNotEmpty()) {
             DiscoveryInfoRow(
-                icon = if (requirements.any { !it.negated }) MaterialSymbols.Lock else MaterialSymbols.LockOpen,
+                icon = if (requirementsLocked) MaterialSymbols.Lock else MaterialSymbols.LockOpen,
                 label = stringResource(Res.string.relay_monitor_requirements),
-                value =
-                    requirements.joinToString { req ->
-                        if (req.negated) "!${req.value}" else req.value
-                    },
+                value = requirementsValue,
             )
         }
 
@@ -151,7 +155,7 @@ fun RelayDiscoveryCard(noteEvent: RelayDiscoveryEvent) {
             DiscoveryInfoRow(
                 icon = MaterialSymbols.Numbers,
                 label = stringResource(Res.string.relay_monitor_supported_nips),
-                value = supportedNips.sorted().joinToString(),
+                value = supportedNipsValue,
             )
         }
 
@@ -160,10 +164,7 @@ fun RelayDiscoveryCard(noteEvent: RelayDiscoveryEvent) {
             DiscoveryInfoRow(
                 icon = MaterialSymbols.Dns,
                 label = stringResource(Res.string.relay_discovery_accepted_kinds),
-                value =
-                    acceptedKinds.joinToString { kind ->
-                        if (kind.negated) "!${kind.kind}" else "${kind.kind}"
-                    },
+                value = acceptedKindsValue,
             )
         }
 
@@ -196,7 +197,7 @@ fun RelayDiscoveryCard(noteEvent: RelayDiscoveryEvent) {
             DiscoveryInfoRow(
                 icon = MaterialSymbols.TravelExplore,
                 label = stringResource(Res.string.relay_discovery_geohash),
-                value = geohashes.joinToString(),
+                value = geohashesValue,
             )
         }