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

package.json

@@ -16,6 +16,7 @@
         "@playwright/test": "^1.40.0",
         "@tailwindcss/forms": "^0.5.2",
         "@tailwindcss/vite": "^4.0.0",
+        "@testing-library/dom": "^10.4.1",
         "@testing-library/react": "^16.1.0",
         "@testing-library/user-event": "^14.5.2",
         "alpinejs": "^3.4.2",
@@ -35,10 +36,21 @@
         "@emoji-mart/react": "^1.1.1",
         "@inertiajs/core": "^1.0.4",
         "@inertiajs/react": "^1.0.4",
+        "@tiptap/extension-code-block-lowlight": "^3.20.0",
+        "@tiptap/extension-image": "^3.20.0",
+        "@tiptap/extension-link": "^3.20.0",
+        "@tiptap/extension-mention": "^3.20.0",
+        "@tiptap/extension-placeholder": "^3.20.0",
+        "@tiptap/extension-underline": "^3.20.0",
+        "@tiptap/react": "^3.20.0",
+        "@tiptap/starter-kit": "^3.20.0",
+        "@tiptap/suggestion": "^3.20.0",
         "emoji-mart": "^5.6.0",
         "framer-motion": "^12.34.0",
+        "lowlight": "^3.3.0",
         "react": "^19.2.4",
         "react-dom": "^19.2.4",
-        "react-markdown": "^10.1.0"
+        "react-markdown": "^10.1.0",
+        "tippy.js": "^6.3.7"
     }
 }