fix: close remaining security gaps, test fixes, frontend integration, event bus

- RCE: move _check_dangerous_imports() BEFORE exec_module() in plugins.py
- verify_ws_origin: reject empty Origin header when CORS configured
- Test: ai_app fixture with permission_registry init for ai_assistant
- Test: login_client sets CSRF token + Origin as client default headers
- Test: SESSION_COOKIE_SECURE=false override + get_settings.cache_clear()
- Test: asyncio_default_test_loop_scope=session fixes event loop closed
- Test: fix 15 assertions (paths, variables, auth expectations)
- Frontend: integrate SavedFilterBar in ContactsList, Mail, Calendar
- Frontend: integrate TagSelector in ContactsList, Mail, Calendar
- Event Bus: add 4 subscribers in system_notif (conversation/participant/reaction)
- Docs: update all analysis reports and FIX-PLAN-V2 to current state

app/core/auth.py

@@ -104,7 +104,10 @@ def verify_ws_origin(websocket) -> bool:
         return True
     origin = websocket.headers.get("origin", "")
     if not origin:
-        return True  # Non-browser clients don't send Origin
+        # Non-browser clients (curl, etc.) don't send Origin.
+        # Reject when CORS is configured — WebSocket should come from a browser.
+        logger.warning("WebSocket connection rejected: missing Origin header")
+        return False
     return origin in allowed_origins