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

database/factories/PostFactory.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace Database\Factories;
+
+use App\Models\Post;
+use App\Models\User;
+use Illuminate\Database\Eloquent\Factories\Factory;
+
+/**
+ * @extends \Illuminate\Database\Eloquent\Factories\Factory<\App\Models\Post>
+ */
+class PostFactory extends Factory
+{
+    protected $model = Post::class;
+
+    public function definition(): array
+    {
+        return [
+            'user_id'         => User::factory(),
+            'type'            => Post::TYPE_TEXT,
+            'visibility'      => Post::VISIBILITY_PUBLIC,
+            'status'          => Post::STATUS_PUBLISHED,
+            'body'            => fake()->paragraph(),
+            'meta'            => null,
+            'reactions_count' => 0,
+            'comments_count'  => 0,
+        ];
+    }
+
+    public function artworkShare(): static
+    {
+        return $this->state(['type' => Post::TYPE_ARTWORK_SHARE]);
+    }
+
+    public function followersOnly(): static
+    {
+        return $this->state(['visibility' => Post::VISIBILITY_FOLLOWERS]);
+    }
+
+    public function private(): static
+    {
+        return $this->state(['visibility' => Post::VISIBILITY_PRIVATE]);
+    }
+}