feat: forum rich-text editor, emoji picker, mentions, discover nav, feed, uploads, profile

Forum:
- TipTap WYSIWYG editor with full toolbar
- @emoji-mart/react emoji picker (consistent with tweets)
- @mention autocomplete with user search API
- Fix PHP 8.4 parse errors in Blade templates
- Fix thread data display (paginator items)
- Align forum page widths to max-w-5xl

Discover:
- Extract shared _nav.blade.php partial
- Add missing nav links to for-you page
- Add Following link for authenticated users

Feed/Posts:
- Post model, controllers, policies, migrations
- Feed page components (PostComposer, FeedCard, etc)
- Post reactions, comments, saves, reports, sharing
- Scheduled publishing support
- Link preview controller

Profile:
- Profile page components (ProfileHero, ProfileTabs)
- Profile API controller

Uploads:
- Upload wizard enhancements
- Scheduled publish picker
- Studio status bar and readiness checklist

app/Http/Controllers/Api/Search/UserSearchController.php

@@ -31,13 +31,14 @@ final class UserSearchController extends Controller
             ->where('is_active', 1)
             ->whereNull('deleted_at')
             ->where(function ($qb) use ($q) {
-                $qb->whereRaw('LOWER(username) LIKE ?', ['%' . strtolower($q) . '%']);
+                $qb->whereRaw('LOWER(username) LIKE ?', ['%' . strtolower($q) . '%'])
+                   ->orWhereRaw('LOWER(name) LIKE ?', ['%' . strtolower($q) . '%']);
             })
             ->with(['profile', 'statistics'])
             ->orderByRaw('LOWER(username) = ? DESC', [strtolower($q)])   // exact match first
             ->orderBy('username')
             ->limit($perPage)
-            ->get(['id', 'username']);
+            ->get(['id', 'username', 'name']);
 
         $data = $users->map(function (User $user) {
             $username       = strtolower((string) ($user->username ?? ''));
@@ -48,6 +49,7 @@ final class UserSearchController extends Controller
                 'id'            => $user->id,
                 'type'          => 'user',
                 'username'      => $username,
+                'name'          => $user->name ?? $username,
                 'avatar_url'    => AvatarUrl::forUser((int) $user->id, $avatarHash, 64),
                 'uploads_count' => $uploadsCount,
                 'profile_url'   => '/@' . $username,