feat: AI photo enhancement (Real-ESRGAN container) + restore original

- new photo-ai service: FastAPI + Real-ESRGAN x2plus on CPU, internal only
- async job queue in server (POST enhance-ai / GET status), 5min timeout, sequential processing
- keep original photo backup (entries.photo_original_path, uploads/.originals), restore-original endpoint
- UI: AI button and restore-original button in enhance modal
- db: photo_original_path column (init.sql, migration.sql, runtime ensure)

public/journal.html

@@ -187,6 +187,8 @@
       <div class="settings-field"><label>Резкость <span id="enhanceSharpVal">0%</span></label><input type="range" id="enhanceSharp" min="0" max="100" value="0"></div>
     </div>
     <div class="card-foot" style="justify-content:flex-end;gap:8px;margin-top:6px">
+      <button type="button" class="btn-primary ghost" id="enhanceRestoreBtn" style="display:none" title="Вернуть исходную фотографию">↩ Вернуть оригинал</button>
+      <button type="button" class="btn-primary ghost" id="enhanceAiBtn" style="display:none" title="ИИ-восстановление (Real-ESRGAN)">🤖 ИИ</button>
       <button type="button" class="btn-primary ghost" id="enhanceAutoBtn" title="Подобрать настройки автоматически">✨ Авто</button>
       <button type="button" class="btn-primary ghost" id="enhanceCancelBtn">Оставить как есть</button>
       <button type="button" class="btn-primary" id="enhanceSaveBtn">Применить</button>