fix: restore all code deleted/truncated by d2217531 Jules SSRF commit

Commit d2217531 (google-labs-jules SSRF fix) catastrophically deleted
11,500+ lines across 100+ files while fixing an unrelated IMAP issue.

Restored from d2217531^ (pre-bad-commit state):

Deleted files (fully restored):
- app/api/{automation,classification_rules,comments,sharing}.py
- app/middleware/upload_rate_limit.py
- app/tasks/{automation_tasks,classify_document}.py
- app/utils/{automation_hooks,classification_rules}.py
- docs/AppleAppStoreCompliance.md
- frontend/input.css, package.json, package-lock.json, tailwind.config.js
- frontend/static/js/{annotations,claim,comments,sharing}.js
- frontend/templates/{admin_connections,file_annotations,file_summary}.html
- tests/{test_api_files_comprehensive,test_auth_extended,test_sharing,
         test_comments,test_connections,test_imap_profiles,test_api_sessions,
         test_automation,test_classification_rules,test_api_advanced_filters,
         test_api_classification_rules,test_upload_rate_limit,test_api_dropbox,
         test_classify_document,test_comments_ui,test_upload_to_icloud,
         test_api_onedrive_comprehensive,test_frontend_build,test_sentry,
         test_diagnostic,test_database,test_views_dropbox,test_local_auth}.py

Truncated files (content restored):
- app/{auth,config,main,models,celery_worker,database}.py
- app/api/{__init__,api_tokens,diagnostic,dropbox,files,google_drive,
           integrations,local_auth,mobile,onedrive,pipelines,qr_auth,
           settings,url_upload}.py
- app/middleware/upload_rate_limit.py
- app/tasks/upload_to_nextcloud.py
- app/utils/{allowed_types,settings_service,settings_sync,user_scope,webhook}.py
- app/views/{base,dropbox,files,google_drive,onedrive,settings}.py
- docs/{API,AuthenticationSetup,ConfigurationGuide,DatabaseConfiguration,
        DeploymentGuide,DropboxSetup,GoogleDriveSetup,KubernetesDeployment,
        MobileApp,OneDriveSetup,ProductionReadiness,SentrySetup,
        SocialLoginSetup,UserGuide}.md
- frontend/static/{js/upload.js,styles.css}
- frontend/templates/{api_tokens,base,devices,dropbox,dropbox_callback,
                      file_view,files,google_drive,onedrive,onedrive_callback,
                      signup}.html
- frontend/translations/en.json
- migrations/env.py
- tests/{conftest,test_api_integrations,test_api_mobile,test_api_settings,
         test_api_tokens,test_audit_logs,test_duplicates,test_imap_tasks,
         test_setup_wizard,test_views_files_comprehensive}.py

Security fixes kept from post-d2217531 commits:
- app/utils/network.py: DNS SSRF fail-secure fix (06b0fced)
- app/utils/file_operations.py: path traversal fix (1018ea17)
- tests/test_imap_tasks.py: re-applied 4 is_private_ip mock patches

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>
Agent-Logs-Url: https://github.com/christianlouis/DocuElevate/sessions/51133dd8-9bec-41ab-aa10-3de753634187

docs/DatabaseConfiguration.md

@@ -337,18 +337,26 @@ The Helm chart includes a pre-install and pre-upgrade Job hook that runs `alembi
 
 ## Connection Pooling
 
-SQLAlchemy manages a connection pool automatically.  The defaults are suitable for most deployments.  For high-concurrency or Kubernetes deployments you may want to tune:
+SQLAlchemy manages a connection pool automatically.  DocuElevate selects the pool
+strategy based on the database backend:
+
+- **SQLite** — uses `NullPool` (a fresh connection per request, closed immediately).
+  This avoids the `QueuePool limit reached` `TimeoutError` that can occur under
+  concurrent load because SQLite does not benefit from persistent connection pooling.
+- **PostgreSQL / MySQL** — uses a bounded `QueuePool` whose size is configurable
+  via environment variables.
 
 ```bash
-# Optional — these are set via environment variables if you extend app/database.py
-# Typical production values:
-DB_POOL_SIZE=10         # Number of persistent connections per worker
-DB_MAX_OVERFLOW=20      # Additional connections allowed beyond pool_size
-DB_POOL_TIMEOUT=30      # Seconds to wait for a connection from the pool
-DB_POOL_RECYCLE=1800    # Recycle connections after 30 minutes (avoids stale connections)
+# Tune these for PostgreSQL / MySQL (ignored when using SQLite):
+DB_POOL_SIZE=10         # Number of persistent connections per worker (default: 10)
+DB_MAX_OVERFLOW=20      # Additional connections allowed beyond pool_size (default: 20)
+DB_POOL_TIMEOUT=30      # Seconds to wait for a connection from the pool (default: 30)
+DB_POOL_RECYCLE=1800    # Recycle connections after 30 minutes (default: 1800)
 ```
 
-> **Note:** These environment variables are not exposed in the default `app/config.py`.  If you need to tune them, extend the database engine creation in `app/database.py`.
+All backends also enable `pool_pre_ping`, which sends a lightweight health-check
+before each connection is handed out.  This detects stale or dropped connections
+and transparently reconnects.
 
 For **PgBouncer** (external connection pooling), point `DATABASE_URL` at your PgBouncer instance and use transaction-mode pooling:
 
@@ -512,4 +520,13 @@ Then retry `alembic upgrade head`.
 
 Either increase `max_connections` in `postgresql.conf` or add PgBouncer in front of PostgreSQL.  The default PostgreSQL `max_connections` is `100`; reduce `DB_POOL_SIZE` per worker to stay within this limit.
 
+### "QueuePool limit reached" TimeoutError (SQLite)
+
+If you see `TimeoutError: QueuePool limit of size 5 overflow 10 reached`, your
+deployment is still running an older version of DocuElevate that used a bounded
+connection pool for SQLite.  Upgrade to the latest release — SQLite now uses
+`NullPool`, which eliminates this error entirely.  If you are already on the
+latest version and are still seeing pool exhaustion, ensure you are not
+overriding the engine creation manually.
+
 For more help, see the [Troubleshooting Guide](Troubleshooting.md).