Fix admin AI nav bug, add rescan feature

- Fix Blade parse error in admin AI settings (Blade was interpreting
  JSON braces in DEFAULT_PROMPT as template tags, breaking the navbar)
  — pass defaultPrompt from controller instead
- Add rescan: POST /nail-polishes/{id}/rescan creates a new import for
  an existing nail polish and updates its fields after AI analysis
- Add KI-Rescan button on collection cards (only if image exists)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/Http/Controllers/Admin/AiSettingController.php

@@ -10,8 +10,9 @@ class AiSettingController extends Controller
 {
     public function show()
     {
-        $ai = AiSetting::get();
-        return view('admin.ai.show', compact('ai'));
+        $ai            = AiSetting::get();
+        $defaultPrompt = AiSetting::DEFAULT_PROMPT;
+        return view('admin.ai.show', compact('ai', 'defaultPrompt'));
     }
 
     public function update(Request $request)