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/Jobs/GenerateDerivativesJob.php

@@ -23,13 +23,14 @@ final class GenerateDerivativesJob implements ShouldQueue
     public function __construct(
         private readonly string $sessionId,
         private readonly string $hash,
-        private readonly int $artworkId
+        private readonly int $artworkId,
+        private readonly ?string $originalFileName = null
     ) {
     }
 
     public function handle(UploadPipelineService $pipeline): void
     {
-        $pipeline->processAndPublish($this->sessionId, $this->hash, $this->artworkId);
+        $pipeline->processAndPublish($this->sessionId, $this->hash, $this->artworkId, $this->originalFileName);
 
         // Auto-tagging is async and must never block publish.
         AutoTagArtworkJob::dispatch($this->artworkId, $this->hash)->afterCommit();