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/config.py

@@ -639,6 +639,25 @@ class Settings(BaseSettings):
         ),
     )
 
+    # System reset / factory reset settings
+    factory_reset_on_startup: bool = Field(
+        default=False,
+        description=(
+            "When enabled, DocuElevate wipes all user data (database rows and "
+            "work-files on disk) on every startup so the instance always comes "
+            "up in a clean, fresh state.  Useful for demo or testing environments. "
+            "Default: False."
+        ),
+    )
+    enable_factory_reset: bool = Field(
+        default=False,
+        description=(
+            "Show the 'System Reset' page in the admin UI.  When enabled, "
+            "administrators can trigger a full data wipe or a wipe-and-reimport "
+            "directly from the web interface.  Default: False."
+        ),
+    )
+
     # PDF/A archival conversion settings
     enable_pdfa_conversion: bool = Field(
         default=False,