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/Observers/ArtworkObserver.php

@@ -7,6 +7,7 @@ namespace App\Observers;
 use App\Models\Artwork;
 use App\Jobs\RecComputeSimilarByTagsJob;
 use App\Jobs\RecComputeSimilarHybridJob;
+use App\Jobs\Posts\AutoUploadPostJob;
 use App\Services\ArtworkSearchIndexer;
 use App\Services\UserStatsService;
 
@@ -48,6 +49,16 @@ class ArtworkObserver
         if ($artwork->is_public && $artwork->published_at) {
             RecComputeSimilarByTagsJob::dispatch($artwork->id)->delay(now()->addSeconds(30));
             RecComputeSimilarHybridJob::dispatch($artwork->id)->delay(now()->addMinutes(1));
+
+            // Auto-upload post: fire only when artwork transitions to published for the first time
+            if ($artwork->wasChanged('published_at') && $artwork->published_at !== null) {
+                $user = $artwork->user;
+                $autoPost = $user?->profile?->auto_post_upload ?? true;
+                if ($autoPost) {
+                    AutoUploadPostJob::dispatch($artwork->id, $artwork->user_id)
+                        ->delay(now()->addSeconds(5));
+                }
+            }
         }
     }