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/Services/Posts/PostAchievementService.php

@@ -0,0 +1,109 @@
+<?php
+
+namespace App\Services\Posts;
+
+use App\Models\Post;
+use App\Models\PostTarget;
+use App\Models\User;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Log;
+
+/**
+ * Creates achievement posts for significant milestones.
+ *
+ * Achievement types stored in post.meta.achievement_type:
+ *   - follower_100 / follower_500 / follower_1000 / follower_5000 / follower_10000
+ *   - artwork_100_views / artwork_1000_views / artwork_1000_favs
+ *   - award_received
+ */
+class PostAchievementService
+{
+    private const FOLLOWER_MILESTONES = [100, 500, 1_000, 5_000, 10_000, 50_000];
+    private const VIEW_MILESTONES     = [100, 1_000, 10_000, 100_000];
+    private const FAV_MILESTONES      = [10, 100, 500, 1_000];
+
+    /**
+     * Check if a follower count crosses a milestone and create an achievement post.
+     */
+    public function maybeFollowerMilestone(User $user, int $newFollowerCount): void
+    {
+        foreach (self::FOLLOWER_MILESTONES as $milestone) {
+            if ($newFollowerCount === $milestone) {
+                $this->createAchievementPost($user, "follower_{$milestone}", [
+                    'milestone' => $milestone,
+                    'message'   => "🎉 Just reached {$milestone} followers! Thank you all!",
+                ]);
+                break;
+            }
+        }
+    }
+
+    /**
+     * Check if an artwork's view count crosses a milestone.
+     */
+    public function maybeArtworkViewMilestone(User $user, int $artworkId, int $newViewCount): void
+    {
+        foreach (self::VIEW_MILESTONES as $milestone) {
+            if ($newViewCount === $milestone) {
+                $this->createAchievementPost($user, "artwork_{$milestone}_views", [
+                    'artwork_id' => $artworkId,
+                    'milestone'  => $milestone,
+                    'message'    => "🎨 One of my artworks just hit {$milestone} views!",
+                ], $artworkId);
+                break;
+            }
+        }
+    }
+
+    /**
+     * Create an achievement post for receiving an award.
+     */
+    public function awardReceived(User $user, string $awardName, ?int $artworkId = null): void
+    {
+        $this->createAchievementPost($user, 'award_received', [
+            'award_name' => $awardName,
+            'artwork_id' => $artworkId,
+            'message'    => "🏆 Just received the \"{$awardName}\" award!",
+        ], $artworkId);
+    }
+
+    // ─────────────────────────────────────────────────────────────────────────
+
+    private function createAchievementPost(
+        User $user,
+        string $achievementType,
+        array $meta,
+        ?int $artworkId = null,
+    ): void {
+        // Deduplicate: don't create the same achievement post twice
+        $exists = Post::where('user_id', $user->id)
+            ->where('type', Post::TYPE_ACHIEVEMENT)
+            ->whereJsonContains('meta->achievement_type', $achievementType)
+            ->exists();
+
+        if ($exists) {
+            return;
+        }
+
+        DB::transaction(function () use ($user, $achievementType, $meta, $artworkId) {
+            $post = Post::create([
+                'user_id'    => $user->id,
+                'type'       => Post::TYPE_ACHIEVEMENT,
+                'visibility' => Post::VISIBILITY_PUBLIC,
+                'body'       => $meta['message'] ?? null,
+                'status'     => Post::STATUS_PUBLISHED,
+                'meta'       => array_merge($meta, ['achievement_type' => $achievementType]),
+            ]);
+
+            if ($artworkId) {
+                PostTarget::create([
+                    'post_id'     => $post->id,
+                    'target_type' => 'artwork',
+                    'target_id'   => $artworkId,
+                ]);
+            }
+        });
+
+        Log::info("PostAchievementService: created '{$achievementType}' post for user #{$user->id}");
+    }
+}