Refreshes .claude/ skill library: fixes stale refs, adds 4 new skills

- Updates CLAUDE.md tech stack to current versions (Compose 1.10.3, Kotlin 2.3.20).
- Reframes kotlin-multiplatform iOS as mature; adds secp256k1-kmp 0.23.0 references.
- Updates desktop-expert Main.kt references (code grew from ~270 to 1341 lines and
  NavigationRail moved to ui/deck/SinglePaneLayout.kt); replaces obsolete
  "hardcoded ctrl = true" anti-pattern note with accurate isMacOS branching.
- Removes compose-desktop.md (superseded by desktop-expert/).
- Adds nostr-expert references: nip19-bech32, event-factory, crypto-and-encryption,
  large-cache. Adds kotlin-expert/common-utilities, compose-expert/rich-text-parsing,
  android-expert/image-loading.
- New skills: account-state (Account + LocalCache), relay-client (subscriptions,
  filter assemblers, preloaders), feed-patterns (FeedFilter + FeedViewModel family),
  auth-signers (NostrSigner across internal / NIP-46 / NIP-55).

.claude/skills/auth-signers/references/nip46-remote-signer.md

@@ -0,0 +1,109 @@
+# NIP-46 Remote Signer (Bunker)
+
+Remote signers are a different Nostr client (the "bunker") that holds the private key and signs on request over Nostr DMs. Amethyst connects to a bunker via a `bunker://` URL and proxies every signing / encryption operation as a request/response over kind 24133 events.
+
+## Layout
+
+`quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip46RemoteSigner/`:
+
+```
+nip46RemoteSigner/
+├── BunkerMessage.kt            ── common wrapper
+├── BunkerRequest.kt            ── sealed base for requests
+├── BunkerRequestConnect.kt
+├── BunkerRequestGetPublicKey.kt
+├── BunkerRequestGetRelays.kt
+├── BunkerRequestNip04Decrypt.kt
+├── BunkerRequestNip04Encrypt.kt
+├── BunkerRequestNip44Decrypt.kt
+├── BunkerRequestNip44Encrypt.kt
+├── BunkerRequestPing.kt
+├── BunkerRequestSign.kt
+├── BunkerResponse.kt           ── sealed base for responses
+├── BunkerResponseAck.kt
+├── BunkerResponseDecrypt.kt
+├── BunkerResponseEncrypt.kt
+├── BunkerResponseError.kt
+├── BunkerResponseEvent.kt
+├── BunkerResponseGetRelays.kt
+├── BunkerResponsePong.kt
+├── BunkerResponsePublicKey.kt
+├── NostrConnectEvent.kt        ── kind 24133 payload
+├── kotlinSerialization/        ── JSON codecs for each request/response
+└── signer/
+    ├── NostrSignerRemote.kt       ── the NostrSigner impl
+    ├── RemoteSignerManager.kt     ── connection lifecycle
+    ├── ConnectResponse.kt
+    ├── Nip04DecryptResponse.kt
+    ├── Nip04EncryptResponse.kt
+    ├── Nip44DecryptResponse.kt
+    ├── Nip44EncryptResponse.kt
+    ├── PingResponse.kt
+    ├── PubKeyResponse.kt
+    ├── SignerResult.kt
+    └── SignResponse.kt
+```
+
+## Connection Flow
+
+```
+User pastes bunker://<bunker-pubkey>?relay=wss://…&secret=…
+              │
+              ▼
+RemoteSignerManager.connect(url) generates a client keypair
+              │
+              ▼
+Publish BunkerRequestConnect (kind 24133, encrypted) to relay
+              │
+              ▼
+Wait for BunkerResponseAck or BunkerResponseError
+              │
+              ▼ on ack
+Return a NostrSignerRemote(clientKeys, bunkerPubKey, relays)
+```
+
+The client keypair is **not** the user's Nostr identity — it's a session key used to correspond with the bunker. The bunker controls the real signing key. `RemoteSignerManager` persists session state so reconnecting skips the handshake.
+
+## Request / Response Pattern
+
+Every signing or encryption call is an async round-trip:
+
+```
+Amethyst                              Bunker
+   │                                   │
+   │── BunkerRequestSign(template) ──►│
+   │                                   │  user approves (sometimes)
+   │◄── BunkerResponseEvent(signed) ──│
+   │                                   │
+```
+
+`NostrSignerRemote.sign(template, onReady)` serializes the `BunkerRequestSign`, encrypts it to the bunker's pubkey, publishes it, and waits (with a timeout) for a `BunkerResponseEvent` carrying the signed event. The response goes through a request-id correlation map so concurrent signs don't interleave.
+
+## Supported Requests
+
+- `BunkerRequestConnect` / `BunkerRequestPing` — lifecycle.
+- `BunkerRequestGetPublicKey` — verify what pubkey this session controls.
+- `BunkerRequestGetRelays` — discover the bunker's preferred inbox relays.
+- `BunkerRequestSign` — the main path.
+- `BunkerRequestNip04Encrypt`/`Decrypt` — legacy DMs.
+- `BunkerRequestNip44Encrypt`/`Decrypt` — NIP-44 payloads (gift-wrap, modern DMs).
+
+Each has a matching response with the same correlation id.
+
+## Timeouts & Disconnects
+
+- **Timeout**: default in `NostrSignerRemote`. Expired requests surface as `SignerExceptions.TimedOut` (or equivalent). Treat as "maybe the user will approve later but UI has given up" — don't auto-retry.
+- **Relay disconnect**: `RemoteSignerManager` reconnects transparently when the bunker's relay reappears; in-flight requests may still time out.
+- **Bunker revoke**: if the bunker closes the session, next sign attempt returns `BunkerResponseError`; prompt the user to reconnect.
+
+## Gotchas
+
+- **The session key is not the user key.** Logs and UI should never surface the session pubkey as "your pubkey".
+- **Don't assume a sign is fast** — UX should show a spinner and allow cancellation for 10+ seconds.
+- **Relay hints from `BunkerRequestGetRelays`** can change the relay list mid-session; the session manager handles it, but re-reads of `relays` in feature code may be stale.
+- **NIP-46 over Nostr is the only transport here** — there's no HTTP/WS shortcut. Any feature gating on "can this sign" must check relay reachability.
+
+## Related
+
+- `nip55-android-signer.md` — the other remote-ish signer (but local to the device).
+- `nostr-expert/references/crypto-and-encryption.md` — NIP-44 details (used by request/response encryption).