feat(system-reset): add system reset and factory reset feature

- Add FACTORY_RESET_ON_STARTUP and ENABLE_FACTORY_RESET config settings
- Create app/utils/system_reset.py with core reset logic (wipe DB + files, reimport)
- Create app/api/system_reset.py with admin-only API endpoints
- Create app/views/system_reset.py with admin-only UI view
- Create frontend/templates/system_reset.html with confirmation dialogs
- Auto-reset on startup when FACTORY_RESET_ON_STARTUP=true
- Re-import uses watch folder mechanism for re-ingestion
- Register routers in API and views init files
- Add i18n keys and SETTING_METADATA entries
- Add nav links in base.html (desktop + mobile)

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

app/views/system_reset.py

@@ -0,0 +1,40 @@
+"""
+System reset view — admin-only UI page.
+
+Renders a confirmation-heavy page that allows administrators to:
+1. **Full Reset** — wipe all user data (DB + disk) for a fresh start.
+2. **Reset & Re-import** — move originals to a reimport folder, wipe,
+   and let the watch-folder mechanism re-ingest them.
+
+Both options are gated behind the ``ENABLE_FACTORY_RESET`` feature flag.
+"""
+
+import logging
+
+from fastapi import Depends, Request
+from fastapi.responses import RedirectResponse, Response
+from sqlalchemy.orm import Session
+
+from app.config import settings
+from app.views.base import APIRouter, get_db, require_login, templates
+from app.views.settings import require_admin_access
+
+logger = logging.getLogger(__name__)
+router = APIRouter()
+
+
+@router.get("/admin/system-reset")
+@require_login
+@require_admin_access
+async def system_reset_page(request: Request, db: Session = Depends(get_db)) -> Response:
+    """Render the system reset administration page."""
+    if not settings.enable_factory_reset:
+        return RedirectResponse(url="/settings", status_code=302)
+
+    return templates.TemplateResponse(
+        "system_reset.html",
+        {
+            "request": request,
+            "factory_reset_on_startup": settings.factory_reset_on_startup,
+        },
+    )