Tool-aggregator writes: treat every 5xx as unknown outcome, not failure

When a non-idempotent write (e.g. a social post or upload) goes through a tool aggregator like Composio's tools/execute REST endpoint, a 500 from the aggregator can arrive after the downstream API already accepted the request (the aggregator fails while handling the downstream answer). Mapping it to 'server error, nothing posted' invites the user to retry and double-post. Map any 5xx (not just 502/503/504), dropped sockets, timeouts and 200s with unreadable bodies to an 'outcome unknown, check before retrying' state, and never auto-retry the write. Keep 4xx and successful:false bodies as definite failures.