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- Removes compose-desktop.md (superseded by desktop-expert/).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/compose-expert/SKILL.md

@@ -520,6 +520,7 @@ fun FeedList(items: List<Item>) {
 - **references/shared-composables-catalog.md** - Complete catalog of shared UI components
 - **references/state-patterns.md** - State management patterns with visual examples
 - **references/icon-assets.md** - Custom ImageVector icon patterns
+- **references/rich-text-parsing.md** - `RichTextParser`, `UrlParser`, `GalleryParser`, `Patterns`, `MediaContentModels`; NIP-92 imeta enrichment
 - **scripts/find-composables.sh** - Find all @Composable functions in codebase
 
 ## Quick Reference