Make Ollama prompt editable in admin AI settings

- Add prompt column to ai_settings (migration)
- AiSetting: DEFAULT_PROMPT constant + getActivePrompt() (falls back to default if empty)
- ProcessNailPolishImage: reads prompt from DB instead of hardcoded
- Admin view: textarea to edit prompt, shows active prompt, reset-to-default link

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

resources/views/admin/ai/show.blade.php

@@ -30,7 +30,7 @@
                         <div class="form-text">URL des Ollama-Containers/Servers ohne abschließenden Slash.</div>
                     </div>
 
-                    <div class="mb-4">
+                    <div class="mb-3">
                         <label class="form-label" for="ollama_model">Modell <span class="text-danger">*</span></label>
                         <input type="text" class="form-control @error('ollama_model') is-invalid @enderror"
                                id="ollama_model" name="ollama_model"
@@ -42,6 +42,28 @@
                         <div class="form-text">Muss ein Vision-fähiges Modell sein (z.B. <code>llama3.2-vision</code>, <code>llava</code>).</div>
                     </div>
 
+                    <div class="mb-4">
+                        <label class="form-label" for="prompt">
+                            Erkennungs-Prompt
+                            <span class="badge bg-secondary ms-1" style="font-size:.65rem;">optional</span>
+                        </label>
+                        <textarea class="form-control @error('prompt') is-invalid @enderror"
+                                  id="prompt" name="prompt" rows="12"
+                                  placeholder="Leer lassen für Standard-Prompt"
+                                  style="font-family: monospace; font-size: .82rem;">{{ old('prompt', $ai->prompt) }}</textarea>
+                        @error('prompt')
+                            <div class="invalid-feedback">{{ $message }}</div>
+                        @enderror
+                        <div class="form-text">
+                            Leer lassen um den Standard-Prompt zu verwenden.
+                            <a href="#" onclick="resetPrompt(); return false;">Standard-Prompt einfügen</a>
+                        </div>
+                        <div class="mt-2 p-3" style="background:#f9fafb; border-radius:10px; border:1px solid #e5e7eb;">
+                            <p style="font-size:.75rem; color:#6b7280; margin:0 0 6px; font-weight:600;">AKTUELL AKTIVER PROMPT:</p>
+                            <pre style="font-size:.75rem; color:#374151; margin:0; white-space:pre-wrap; word-break:break-word;">{{ $ai->getActivePrompt() }}</pre>
+                        </div>
+                    </div>
+
                     <button type="submit" class="btn btn-primary">
                         <i class="fas fa-save me-2"></i>Speichern
                     </button>
@@ -69,4 +91,10 @@
     </div>
 </div>
 
+@section('scripts')
+<script>
+function resetPrompt() {
+    document.getElementById('prompt').value = @json(\App\Models\AiSetting::DEFAULT_PROMPT);
+}
+</script>
 @endsection