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

packages/web/src/api/client.ts

@@ -23,6 +23,8 @@ import type {
   LiveKitTokenResponse,
   CreateDmRequest,
   CreateDmMessageRequest,
+  Friend,
+  FriendRequest,
 } from '@opencord/shared';
 
 const BASE_URL = '/api';
@@ -110,6 +112,7 @@ export const api = {
     delete: (id: string) => request<{ success: boolean }>('DELETE', `/servers/${id}`),
     invite: (id: string) => request<{ inviteCode: string }>('POST', `/servers/${id}/invite`),
     join: (id: string, data: JoinServerRequest) => request<Server>('POST', `/servers/${id}/join`, data),
+    joinByCode: (inviteCode: string) => request<Server>('POST', '/servers/join', { inviteCode }),
     members: (id: string) => request<MemberWithUser[]>('GET', `/servers/${id}/members`),
     updateMember: (serverId: string, userId: string, data: UpdateMemberRequest) =>
       request<MemberWithUser>('PATCH', `/servers/${serverId}/members/${userId}`, data),
@@ -156,6 +159,17 @@ export const api = {
       request<DmMessageWithUser>('POST', `/dm/${id}/messages`, data),
   },
 
+  social: {
+    friends: () => request<Friend[]>('GET', '/social/friends'),
+    requests: () => request<FriendRequest[]>('GET', '/social/requests'),
+    sendRequest: (username: string) => request<{ success: boolean }>('POST', '/social/requests', { username }),
+    updateRequest: (id: string, status: 'accepted' | 'declined') =>
+      request<{ success: boolean }>('PATCH', `/social/requests/${id}`, { status }),
+    removeFriend: (id: string) => request<{ success: boolean }>('DELETE', `/social/friends/${id}`),
+    cancelRequest: (id: string) => request<{ success: boolean }>('DELETE', `/social/requests/${id}`),
+    search: (q: string) => request<User[]>('GET', `/social/search?q=${encodeURIComponent(q)}`),
+  },
+
   livekit: {
     token: (channelId: string) =>
       request<LiveKitTokenResponse>('POST', '/livekit/token', { channelId }),