fix(api): document missing HTTP status codes on router endpoints

Schemathesis was failing CI on routes that returned status codes not
declared in their OpenAPI responses= dicts. Adds the missing codes
across swarm_updates, swarm_mgmt, swarm, fleet and attackers routers.

Also adds 400 to every POST/PUT/PATCH that accepts a JSON body —
Starlette returns 400 on malformed/non-UTF8 bodies before FastAPI's
422 validation runs, which schemathesis fuzzing trips every time.

No handler logic changed.

decnet/web/router/attackers/api_get_attacker_commands.py

@@ -15,6 +15,7 @@ router = APIRouter()
         401: {"description": "Could not validate credentials"},
         403: {"description": "Insufficient permissions"},
         404: {"description": "Attacker not found"},
+        422: {"description": "Query parameter validation error (limit/offset out of range or invalid)"},
     },
 )
 @_traced("api.get_attacker_commands")