fix: repair invite links, social features, messaging + Discord UI overhaul

Phase 1 - Feature Repair:
- Fix member kick/leave: add missing db.delete() call in servers.ts
- Stabilize invite codes: return existing code instead of regenerating
- Fix user search: use LIKE instead of exact match in social.ts
- Wire DM button on FriendsPage to create/navigate to DM channels
- Add cancel outgoing friend request (DELETE endpoint + frontend)
- Add accept/decline friend request actions with WS real-time events
- Fix replyToId persistence in message creation
- Hydrate reactions and replyTo in message queries
- Add joinByCode to API client and serverStore
- Add friend_request_received/accepted WebSocket events

Phase 2 - Discord UI Overhaul:
- Remove stray borders between layout columns
- Replace shadow-sm with shadow-header on content headers
- Replace all bg-gray-*/text-gray-* with Discord color tokens
- Ensure flat color contrast (#1E1F22, #2B2D31, #313338)

Testing:
- Set up vitest + @testing-library/react + jsdom
- Add 17 tests across InviteModal, JoinServer, FriendsPage (all passing)
- Fix vite resolve.extensions to prefer .tsx over stale .js files

docker-compose.yml

@@ -6,7 +6,7 @@ services:
     container_name: opencord
     restart: unless-stopped
     ports:
-      - "${PORT:-3000}:3000"
+      - "${PORT:-3000}:${PORT:-3000}"
     volumes:
       - opencord-data:/app/data
     env_file:
@@ -16,7 +16,7 @@ services:
       - DB_PATH=/app/data/opencord.db
       - UPLOAD_DIR=/app/data/uploads
     healthcheck:
-      test: ["CMD", "node", "-e", "fetch('http://localhost:3000/api/health').then(r => r.ok ? process.exit(0) : process.exit(1)).catch(() => process.exit(1))"]
+      test: ["CMD", "node", "-e", "fetch('http://localhost:${PORT:-3000}/api/health').then(r => r.ok ? process.exit(0) : process.exit(1)).catch(() => process.exit(1))"]
       interval: 30s
       timeout: 5s
       retries: 3