fix: comprehensive system audit fixes (55+ issues)

CRITICAL:
- Fix SQL injection in prestart.sh (parameterized query)
- Fix secret key validation (always validate, not just production)
- Fix workspace model partial index bug (func.text -> text)
- Fix HealthResponse schema (add checks field)
- Fix Tenant import in permissions.py (NameError on every auth request)
- Fix README tech stack (React instead of Alpine.js)
- Delete broken test_cross_tenant_security_v2.py
- Add fail-closed RLS migration 0084 (48 tenant tables)

HIGH:
- Add GeneralRateLimitMiddleware for all API routes
- Add file type blocklist for DMS and attachment uploads
- Fix guest auth: Pydantic schema, tenant_slug required, CSRF bypass
- Fix CSRF bypass path matching (in -> endswith)
- Add worker healthcheck in docker-compose.yml
- Add ARQ max_tries=3 for job retries
- Fix 28 bare pass in mail services (-> logger.debug)
- Fix print() -> logger in main.py and ai_assistant
- Fix duplicate email handling (catch IntegrityError -> 409)
- Add session revocation (invalidate_all_user_sessions)
- Add resource limits to all containers
- Fix CORS default (localhost -> production domain)
- Fix SameSite=Lax -> Strict
- Fix Redis password visibility in healthcheck
- Fix npm vulnerabilities (19 -> 9)
- Fix Sidebar OOM (wildcard lucide import -> curated ICON_MAP)

MEDIUM:
- Localize ErrorBoundary to German
- Wire Mail.tsx save/delete filter to API
- Document system_notif plugin (no routes needed)
- Fix datetime.utcnow() -> datetime.now(UTC)
- Pin litellm version (>=1.0,<2.0)
- Move CSRF token from sessionStorage to in-memory
- Fix restore_backup error handling and transaction
- Fix Dms.tsx useEffect cleanup
- Add skip-to-content link for accessibility
- Add selectinload imports to 3 services
- Add .env.example missing variables
- Fix AppShell/TopBar/Sidebar test mocks

NEW TESTS:
- test_guest_auth.py (6 tests)
- test_user_service.py (8 tests)
- test_backup_service.py (5 tests)

NEW SCHEMAS:
- saved_filter, saved_view, user_preference, workspace, entity_policy

Tests: 22/22 PASSED

app/plugins/builtins/dms/routes.py

@@ -93,6 +93,19 @@ def _sanitize_filename(filename: str) -> str:
         safe = name[:200] + ('.' + ext if ext else '')
     return safe or 'file'
 
+# Blocked file extensions for security
+BLOCKED_EXTENSIONS = {
+    ".exe", ".bat", ".cmd", ".sh", ".jar", ".com", ".scr", ".msi",
+    ".dll", ".vbs", ".ps1", ".app", ".bin", ".reg", ".inf",
+}
+
+
+def _is_blocked_filetype(filename: str) -> bool:
+    """Check if a file has a blocked (dangerous) extension."""
+    ext = os.path.splitext(filename)[1].lower()
+    return ext in BLOCKED_EXTENSIONS
+
+
 CHUNK_SIZE = 1024 * 1024  # 1MB chunks for streaming uploads
 
 # ─── Folders ───
@@ -447,6 +460,13 @@ async def upload_file(
     user_id = uuid.UUID(current_user["user_id"])
     fid = _parse_uuid(folder_id, "folder_id") if folder_id else None
 
+    # Check for blocked file types
+    if _is_blocked_filetype(file.filename or ""):
+        raise HTTPException(
+            400,
+            detail={"detail": "File type not allowed", "code": "blocked_filetype"},
+        )
+
     # Validate folder exists if specified
     if fid is not None:
         folder_result = await db.execute(