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/Posts/PostReportController.php

@@ -0,0 +1,49 @@
+<?php
+
+namespace App\Http\Controllers\Api\Posts;
+
+use App\Http\Controllers\Controller;
+use App\Models\Post;
+use App\Models\PostReport;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+use Illuminate\Support\Facades\Gate;
+
+class PostReportController extends Controller
+{
+    /**
+     * POST /api/posts/{id}/report
+     * payload: { reason, message? }
+     */
+    public function store(Request $request, int $id): JsonResponse
+    {
+        $user = $request->user();
+        $post = Post::findOrFail($id);
+
+        Gate::authorize('report', $post);
+
+        $request->validate([
+            'reason'  => ['required', 'string', 'max:64'],
+            'message' => ['nullable', 'string', 'max:1000'],
+        ]);
+
+        // Unique report per user+post
+        $existing = PostReport::where('post_id', $post->id)
+            ->where('reporter_user_id', $user->id)
+            ->exists();
+
+        if ($existing) {
+            return response()->json(['message' => 'You have already reported this post.'], 409);
+        }
+
+        PostReport::create([
+            'post_id'          => $post->id,
+            'reporter_user_id' => $user->id,
+            'reason'           => $request->input('reason'),
+            'message'          => $request->input('message'),
+            'status'           => 'open',
+        ]);
+
+        return response()->json(['message' => 'Report submitted. Thank you for helping keep Skinbase safe.'], 201);
+    }
+}