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

resources/js/components/artwork/ArtworkActionBar.jsx

@@ -196,6 +196,7 @@ export default function ArtworkActionBar({ artwork, stats, canonicalUrl, onStats
   const [reporting, setReporting] = useState(false)
   const [reported, setReported] = useState(false)
   const [reportOpen, setReportOpen] = useState(false)
+  const isLoggedIn = artwork?.viewer != null
   useEffect(() => {
     setFavorited(Boolean(artwork?.viewer?.is_favorited))
   }, [artwork?.id, artwork?.viewer?.is_favorited])
@@ -311,7 +312,7 @@ export default function ArtworkActionBar({ artwork, stats, canonicalUrl, onStats
         </div>
 
         {/* Share pill */}
-        <ArtworkShareButton artwork={artwork} shareUrl={shareUrl} size="default" />
+        <ArtworkShareButton artwork={artwork} shareUrl={shareUrl} size="default" isLoggedIn={isLoggedIn} />
 
         {/* Report pill */}
         <button
@@ -362,7 +363,7 @@ export default function ArtworkActionBar({ artwork, stats, canonicalUrl, onStats
           </button>
 
           {/* Share */}
-          <ArtworkShareButton artwork={artwork} shareUrl={shareUrl} size="small" />
+          <ArtworkShareButton artwork={artwork} shareUrl={shareUrl} size="small" isLoggedIn={isLoggedIn} />
 
           {/* Report */}
           <button