feat: implement unified chat system with NIP-C7 and NIP-29 support

Core Architecture:
- Protocol adapter pattern for chat implementations
- Base adapter interface with protocol-specific implementations
- Auto-detection of protocol from identifier format
- Reactive message loading via EventStore observables

Protocol Implementations:
- NIP-C7 adapter: Simple chat (kind 9) with npub/nprofile support
- NIP-29 adapter: Relay-based groups with member roles and moderation
- Protocol-aware reply message loading with relay hints
- Proper NIP-29 members/admins fetching using #d tags

UI Components:
- ChatViewer: Main chat interface with virtualized message timeline
- ChatMessage: Message rendering with reply preview
- ReplyPreview: Auto-loading replied-to messages from relays
- MembersDropdown: Virtualized member list with role labels
- RelaysDropdown: Connection status for chat relays
- ChatComposer: Message input with send functionality

Command System:
- chat command with identifier parsing and auto-detection
- Support for npub, nprofile, NIP-05, and relay'group-id formats
- Integration with window system and dynamic titles

NIP-29 Specific:
- Fetch kind:39000 (metadata), kind:39001 (admins), kind:39002 (members)
- Extract roles from p tags: ["p", "<pubkey>", "<role1>", "<role2>"]
- Role normalization (admin, moderator, host, member)
- Single group relay connection management

Testing:
- Comprehensive chat parser tests
- Protocol adapter test structure
- All tests passing (704 tests)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/components/ui/textarea.tsx

@@ -9,7 +9,7 @@ const Textarea = React.forwardRef<
   return (
     <textarea
       className={cn(
-        "flex min-h-[60px] w-full rounded-md border border-input bg-transparent px-3 py-2 text-base shadow-sm transition-colors placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-ring disabled:cursor-not-allowed disabled:opacity-50 md:text-sm",
+        "flex bg-transparent p-2 text-base transition-colors placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-ring disabled:cursor-not-allowed disabled:opacity-50 md:text-sm",
         className,
       )}
       ref={ref}