feat: NIP-51 group lists, profile chat rooms tab, discover groups

[barrydeen]

Summary

• Publish/subscribe NIP-51 kind 10009 (simple groups) lists so chat room membership syncs across clients — on join/leave/create/delete the list is broadcast to write + indexer relays, and populated from self-data on startup
• Add "Chat Rooms" tab to user profiles — fetches kind 10009 from outbox/indexer relays and renders each group with metadata, picture, and member avatars using a shared GroupCard component extracted from RichContent
• Simplify join chat room dialog to accept a single invite link field (parsed via Nip29.parseGroupIdentifier) instead of separate relay URL and group ID fields
• Add "Discover chat rooms" option — queries all known group relays for kind 39000 metadata and 39002 members, deduplicates, and shows results ranked by member count in a bottom sheet

Test plan

• Join a chat room and verify kind 10009 is published to relays
• Leave a chat room and verify kind 10009 is updated
• Log out and back in — verify joined groups are restored from kind 10009
• Visit another user's profile — verify "Chat Rooms" tab shows their groups with metadata
• Paste an invite link in the join dialog and verify it parses correctly
• Open "Discover chat rooms" multiple times — verify results load consistently
• Tap a discovered room to join it