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/core/rate_limit.py

@@ -1,11 +1,17 @@
-"""Redis-based rate limiting for auth endpoints."""
+"""Redis-based rate limiting for auth endpoints and general API."""
 
 from __future__ import annotations
 
+import logging
+
 from fastapi import HTTPException, Request, status
+from starlette.middleware.base import BaseHTTPMiddleware
+from starlette.responses import JSONResponse
 
 from app.core.auth import get_redis
 
+logger = logging.getLogger(__name__)
+
 
 async def check_rate_limit(
     redis_key: str,
@@ -74,3 +80,39 @@ def get_client_ip(request: Request) -> str:
 
     # Not a trusted proxy or no trusted proxies configured — use direct IP
     return direct_ip
+
+
+class GeneralRateLimitMiddleware(BaseHTTPMiddleware):
+    """Apply general rate limiting to all API routes."""
+
+    # Paths to skip rate limiting
+    SKIP_PATHS = {"/api/v1/health", "/api/v1/health/live", "/api/v1/health/ready", "/api/v1/metrics"}
+
+    async def dispatch(self, request: Request, call_next):
+        from app.config import get_settings
+        settings = get_settings()
+        path = request.url.path
+
+        # Skip health and metrics endpoints
+        if path in self.SKIP_PATHS or path.startswith("/docs") or path.startswith("/redoc"):
+            return await call_next(request)
+
+        # Only rate limit API routes
+        if not path.startswith("/api/"):
+            return await call_next(request)
+
+        try:
+            ip = get_client_ip(request)
+            await check_rate_limit(
+                f"rate:general:{ip}",
+                settings.rate_limit_general_max,
+                settings.rate_limit_general_window,
+            )
+        except HTTPException as exc:
+            return JSONResponse(
+                status_code=exc.status_code,
+                content=exc.detail,
+                headers=exc.headers,
+            )
+
+        return await call_next(request)