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/components/layout/MainContent.tsx

@@ -6,6 +6,7 @@ import { MessageList } from '../chat/MessageList';
 import { MessageInput } from '../chat/MessageInput';
 import { TypingIndicator } from '../chat/TypingIndicator';
 import { VoiceGrid } from '../voice/VoiceGrid';
+import { FriendsPage } from '../chat/FriendsPage';
 import { useVoiceStore } from '../../stores/voiceStore';
 
 export function MainContent() {
@@ -14,7 +15,7 @@ export function MainContent() {
   const currentServerId = useServerStore((s) => s.currentServerId);
   const toggleMemberList = useUIStore((s) => s.toggleMemberList);
   const memberListOpen = useUIStore((s) => s.memberListOpen);
-  const currentVoiceChannelId = useVoiceStore((s) => s.currentVoiceChannelId);
+  const participants = useVoiceStore((s) => s.participants);
   const showDms = useUIStore((s) => s.showDms);
 
   const channel = channels.find(c => c.id === currentChannelId);
@@ -22,17 +23,21 @@ export function MainContent() {
 
   // DM view or no server selected
   if (showDms || !currentServerId) {
+    if (!currentChannelId) {
+      return <FriendsPage />;
+    }
+    
     return (
-      <div className="flex-1 flex flex-col bg-discord-bg-primary">
-        <div className="h-12 px-4 flex items-center border-b border-discord-bg-tertiary shadow-sm">
-          <span className="font-bold text-discord-text-primary">Home</span>
-        </div>
-        <div className="flex-1 flex items-center justify-center text-discord-text-muted">
-          <div className="text-center">
-            <h2 className="text-2xl font-bold text-discord-text-primary mb-2">Welcome to Opencord!</h2>
-            <p>Select a server from the sidebar or start a direct message.</p>
+      <div className="flex-1 flex flex-col bg-discord-bg-primary min-w-0 relative">
+        <div className="h-12 px-4 flex items-center shadow-header flex-shrink-0 z-10">
+          <div className="flex items-center gap-2 min-w-0">
+            <span className="text-discord-text-muted font-bold text-lg">@</span>
+            <span className="font-bold text-discord-text-primary truncate">Direct Message</span>
           </div>
         </div>
+        <MessageList channelId={currentChannelId} />
+        <TypingIndicator channelId={currentChannelId} />
+        <MessageInput channelId={currentChannelId} channelName="Direct Message" />
       </div>
     );
   }
@@ -41,7 +46,7 @@ export function MainContent() {
   if (!currentChannelId || !channel) {
     return (
       <div className="flex-1 flex flex-col bg-discord-bg-primary">
-        <div className="h-12 px-4 flex items-center border-b border-discord-bg-tertiary shadow-sm">
+        <div className="h-12 px-4 flex items-center shadow-header">
           <span className="text-discord-text-muted">Select a channel</span>
         </div>
         <div className="flex-1 flex items-center justify-center text-discord-text-muted">
@@ -55,7 +60,7 @@ export function MainContent() {
   if (isVoiceChannel) {
     return (
       <div className="flex-1 flex flex-col bg-discord-bg-primary">
-        <div className="h-12 px-4 flex items-center justify-between border-b border-discord-bg-tertiary shadow-sm">
+        <div className="h-12 px-4 flex items-center justify-between shadow-header">
           <div className="flex items-center gap-2">
             <svg width="24" height="24" viewBox="0 0 24 24" fill="currentColor" className="text-discord-text-muted">
               <path d="M11 5L6 9H2V15H6L11 19V5ZM15.54 8.46C16.48 9.4 17 10.67 17 12S16.48 14.6 15.54 15.54L14.12 14.12C14.69 13.55 15 12.79 15 12S14.69 10.45 14.12 9.88L15.54 8.46Z" />
@@ -63,33 +68,33 @@ export function MainContent() {
             <span className="font-bold text-discord-text-primary">{channel.name}</span>
           </div>
         </div>
-        <VoiceGrid participants={[]} />
+        <VoiceGrid participants={participants} />
       </div>
     );
   }
 
   // Text channel view
   return (
-    <div className="flex-1 flex flex-col bg-discord-bg-primary min-w-0">
+    <div className="flex-1 flex flex-col bg-discord-bg-primary min-w-0 relative">
       {/* Channel header */}
-      <div className="h-12 px-4 flex items-center justify-between border-b border-discord-bg-tertiary shadow-sm flex-shrink-0">
+      <div className="h-12 px-4 flex items-center justify-between shadow-header flex-shrink-0 z-10 bg-discord-bg-primary">
         <div className="flex items-center gap-2 min-w-0">
           <svg width="24" height="24" viewBox="0 0 24 24" fill="currentColor" className="text-discord-text-muted flex-shrink-0">
             <path d="M5.88657 21C5.57547 21 5.3399 20.7189 5.39427 20.4126L6.00001 17H2.59511C2.28449 17 2.04905 16.7198 2.10259 16.4138L2.27759 15.4138C2.31946 15.1746 2.52722 15 2.77011 15H6.35001L7.41001 9H4.00511C3.69449 9 3.45905 8.71977 3.51259 8.41381L3.68759 7.41381C3.72946 7.17456 3.93722 7 4.18011 7H7.76001L8.39677 3.41262C8.43914 3.17391 8.64664 3 8.88907 3H9.87344C10.1845 3 10.4201 3.28107 10.3657 3.58738L9.76001 7H15.76L16.3968 3.41262C16.4391 3.17391 16.6466 3 16.8891 3H17.8734C18.1845 3 18.4201 3.28107 18.3657 3.58738L17.76 7H21.1649C21.4755 7 21.711 7.28023 21.6574 7.58619L21.4824 8.58619C21.4406 8.82544 21.2328 9 20.9899 9H17.41L16.35 15H19.7549C20.0655 15 20.301 15.2802 20.2474 15.5862L20.0724 16.5862C20.0306 16.8254 19.8228 17 19.5799 17H16L15.3632 20.5874C15.3209 20.8261 15.1134 21 14.8709 21H13.8866C13.5755 21 13.3399 20.7189 13.3943 20.4126L14 17H8.00001L7.36325 20.5874C7.32088 20.8261 7.11337 21 6.87094 21H5.88657ZM9.41001 9L8.35001 15H14.35L15.41 9H9.41001Z" />
           </svg>
-          <span className="font-bold text-discord-text-primary truncate">{channel.name}</span>
+          <span className="font-bold text-discord-text-primary truncate leading-tight">{channel.name}</span>
           {channel.topic && (
             <>
-              <div className="w-px h-6 bg-discord-bg-hover mx-1" />
-              <span className="text-xs text-discord-text-muted truncate">{channel.topic}</span>
+              <div className="w-[1px] h-6 bg-discord-bg-accent mx-2" />
+              <span className="text-xs text-discord-text-muted truncate leading-tight">{channel.topic}</span>
             </>
           )}
         </div>
-        <div className="flex items-center gap-2 flex-shrink-0">
+        <div className="flex items-center gap-4 flex-shrink-0">
           <button
             onClick={toggleMemberList}
             className={`p-1 transition-colors ${
-              memberListOpen ? 'text-discord-text-primary' : 'text-discord-text-muted hover:text-discord-text-primary'
+              memberListOpen ? 'text-discord-text-primary' : 'text-discord-text-muted hover:text-discord-text-secondary'
             }`}
             title="Toggle Member List"
           >