feat(amethyst): scaffold NIP-60 Cashu wallet UI + state

Adds the user-visible scaffolding for a Cashu wallet alongside the
existing NWC wallets. View-only for now — minting, send/receive, and
NIP-61 nutzaps land in a follow-up commit on this branch.

UI
  * AddWalletScreen is now a wallet-type chooser. The existing NWC
    flow moves verbatim to AddNwcWalletScreen; AddCashuWalletScreen
    is new: takes one or more mint URLs, auto-generates a separate
    P2PK key for nutzap receiving (or accepts a pasted hex key), and
    publishes a kind:17375 wallet event via the account's signer
    using CashuWalletEvent.build(mints, privkey).
  * CashuWalletScreen renders the wallet's mint list, total balance
    in sats (summed across all unspent kind:7375 token events the
    signer can decrypt, with rollover applied via the `del` field),
    and a chronological history view sourced from kind:7376.
  * WalletScreen surfaces the Cashu wallet as a card under "Your
    Wallets" when one exists, so the Wallets entry point shows both
    wallet kinds side by side.

Relay subscription
  * CashuWalletFilterAssembler (commons) subscribes one filter per
    relay covering kinds 17375/7375/7376/7374/10019 by author and
    one targeting inbound kind:9321 via #p. Not yet wired into
    Account.kt — the view path works because we feed our own writes
    through cache.justConsumeMyOwnEvent. Cross-device sync requires
    the assembler subscription wiring, which comes next.

Plumbing
  * Routes.WalletAddNwc / WalletAddCashu / CashuWallet added and
    registered in AppNavigation.
  * CashuWalletEvent.createAddress(pubKey) mirrors MetadataEvent for
    looking up the replaceable wallet event from LocalCache.

Compiles clean on playDebug + fdroidDebug; BDHKE jvm tests still
pass (7/7).

https://claude.ai/code/session_01MdWddiar819f8XYt5N8BjP

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/relayClient/assemblers/CashuWalletFilterAssembler.kt

@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.commons.relayClient.assemblers
+
+import com.vitorpamplona.amethyst.commons.relayClient.eoseManagers.SingleSubEoseManager
+import com.vitorpamplona.amethyst.commons.relays.SincePerRelayMap
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip01Core.relay.client.INostrClient
+import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
+import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+import com.vitorpamplona.quartz.nip60Cashu.history.CashuSpendingHistoryEvent
+import com.vitorpamplona.quartz.nip60Cashu.quote.CashuMintQuoteEvent
+import com.vitorpamplona.quartz.nip60Cashu.token.CashuTokenEvent
+import com.vitorpamplona.quartz.nip60Cashu.wallet.CashuWalletEvent
+import com.vitorpamplona.quartz.nip61Nutzaps.info.NutzapInfoEvent
+import com.vitorpamplona.quartz.nip61Nutzaps.nutzap.NutzapEvent
+
+/**
+ * Query state for the NIP-60 / NIP-61 wallet subscription.
+ *
+ * `pubkey` is the wallet owner — used both as `authors=` for their own
+ * NIP-60 events and as the `#p` tag value for inbound nutzaps.
+ */
+data class CashuWalletQueryState(
+    val pubkey: HexKey,
+    val relays: Set<NormalizedRelayUrl>,
+)
+
+/**
+ * Subscribes to all NIP-60 / NIP-61 events that participate in this
+ * account's Cashu wallet:
+ *
+ *  - kind 17375 — the wallet event (replaceable)
+ *  - kind 7375  — unspent proofs (token events)
+ *  - kind 7376  — spending history
+ *  - kind 7374  — quote state events
+ *  - kind 10019 — nutzap info (replaceable, for incoming nutzaps)
+ *  - kind 9321  — inbound nutzaps tagged with the user's pubkey
+ *
+ * All authored events are queried by `authors=[pubkey]`; nutzaps are queried by
+ * `#p=[pubkey]` (we receive them, not send them, from this filter's perspective).
+ */
+class CashuWalletFilterAssembler(
+    client: INostrClient,
+    allKeys: () -> Set<CashuWalletQueryState>,
+) : SingleSubEoseManager<CashuWalletQueryState>(client, allKeys, invalidateAfterEose = true) {
+    override fun distinct(key: CashuWalletQueryState): Any = key.pubkey
+
+    override fun updateFilter(
+        keys: List<CashuWalletQueryState>,
+        since: SincePerRelayMap?,
+    ): List<RelayBasedFilter>? {
+        if (keys.isEmpty()) return null
+
+        val pubkey = keys.first().pubkey
+        val relays =
+            keys
+                .flatMap { it.relays }
+                .toSet()
+                .ifEmpty { return null }
+
+        val ownedFilter =
+            Filter(
+                kinds =
+                    listOf(
+                        CashuWalletEvent.KIND,
+                        CashuTokenEvent.KIND,
+                        CashuSpendingHistoryEvent.KIND,
+                        CashuMintQuoteEvent.KIND,
+                        NutzapInfoEvent.KIND,
+                    ),
+                authors = listOf(pubkey),
+            )
+
+        val inboundNutzapsFilter =
+            Filter(
+                kinds = listOf(NutzapEvent.KIND),
+                tags = mapOf("p" to listOf(pubkey)),
+            )
+
+        return relays.flatMap { relay ->
+            val sinceTime = since?.get(relay)?.time
+            listOf(
+                RelayBasedFilter(
+                    relay,
+                    if (sinceTime != null) ownedFilter.copy(since = sinceTime) else ownedFilter,
+                ),
+                RelayBasedFilter(
+                    relay,
+                    if (sinceTime != null) inboundNutzapsFilter.copy(since = sinceTime) else inboundNutzapsFilter,
+                ),
+            )
+        }
+    }
+}