feat(clink): let users set a noffer on their profile

Adds a 'CLINK Offer (noffer)' field to the profile editor so users can advertise
a payment offer in their kind-0 metadata:
- UserMetadataState.sendNewUserMetadata threads clinkOffer into the kind-0 build.
- NewUserMetadataViewModel loads/saves/clears the clinkOffer field.
- NewUserMetadataScreen renders the input (placeholder noffer1…).

:amethyst compiles. The read side (NIP-05 clink_offer discovery + preferring it)
is the next step.

amethyst/src/main/java/com/vitorpamplona/amethyst/model/nip01UserMetadata/UserMetadataState.kt

@@ -68,6 +68,7 @@ class UserMetadataState(
         nip05: String? = null,
         lnAddress: String? = null,
         lnURL: String? = null,
+        clinkOffer: String? = null,
     ): MetadataEvent {
         val latest = getUserMetadataEvent()
 
@@ -85,6 +86,7 @@ class UserMetadataState(
                     nip05 = nip05,
                     lnAddress = lnAddress,
                     lnURL = lnURL,
+                    clinkOffer = clinkOffer,
                 )
             } else {
                 MetadataEvent.createNew(
@@ -98,6 +100,7 @@ class UserMetadataState(
                     nip05 = nip05,
                     lnAddress = lnAddress,
                     lnURL = lnURL,
+                    clinkOffer = clinkOffer,
                 )
             }
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/actions/NewUserMetadataScreen.kt

@@ -303,6 +303,22 @@ fun NewUserMetadataScreen(
                     singleLine = true,
                 )
 
+                Spacer(modifier = Modifier.height(10.dp))
+
+                OutlinedTextField(
+                    label = { Text(text = stringRes(R.string.clink_offer_label)) },
+                    modifier = Modifier.fillMaxWidth(),
+                    value = postViewModel.clinkOffer.value,
+                    onValueChange = { postViewModel.clinkOffer.value = it },
+                    placeholder = {
+                        Text(
+                            text = "noffer1…",
+                            color = MaterialTheme.colorScheme.placeholderText,
+                        )
+                    },
+                    singleLine = true,
+                )
+
                 // -- Social Proofs --
                 ExpandableSection(
                     title = stringRes(R.string.social_proof),

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/actions/NewUserMetadataViewModel.kt

@@ -60,6 +60,7 @@ class NewUserMetadataViewModel : ViewModel() {
     val nip05 = mutableStateOf("")
     val lnAddress = mutableStateOf("")
     val lnURL = mutableStateOf("")
+    val clinkOffer = mutableStateOf("")
 
     val twitter = mutableStateOf("")
     val github = mutableStateOf("")
@@ -85,6 +86,7 @@ class NewUserMetadataViewModel : ViewModel() {
             nip05.value = it.info.nip05 ?: ""
             lnAddress.value = it.info.lud16 ?: ""
             lnURL.value = it.info.lud06 ?: ""
+            clinkOffer.value = it.info.clinkOffer ?: ""
         }
 
         twitter.value = ""
@@ -124,6 +126,7 @@ class NewUserMetadataViewModel : ViewModel() {
                 nip05 = nip05.value,
                 lnAddress = lnAddress.value,
                 lnURL = lnURL.value,
+                clinkOffer = clinkOffer.value,
             )
 
         val identities =
@@ -149,6 +152,7 @@ class NewUserMetadataViewModel : ViewModel() {
         nip05.value = ""
         lnAddress.value = ""
         lnURL.value = ""
+        clinkOffer.value = ""
         twitter.value = ""
         github.value = ""
         mastodon.value = ""

amethyst/src/main/res/values/strings.xml

@@ -121,6 +121,7 @@
     <string name="clink_offer_amount_sats">Amount (sats)</string>
     <string name="clink_offer_invalid_amount">Enter a valid amount for this offer.</string>
     <string name="clink_offer_amount_range">Allowed range: %1$s–%2$s sats</string>
+    <string name="clink_offer_label">CLINK Offer (noffer)</string>
     <string name="clink_debit_pay_only">Pay only</string>
     <string name="wallet_add_clink_title">CLINK Debit</string>
     <string name="wallet_add_clink_description">Pay and zap from a wallet that pre-authorized your account. Spend only — no balance or history.</string>