v0.4.1

Release notes — ceph-aiops 0.4.1

Previous release: 0.4.0.

Fixed: pool_df reported a failed query as "no pools"

It caught every exception and returned an empty list, so a flaky mgr was
indistinguishable from a cluster that genuinely has no pools — the failure read as
"nothing to worry about".

BREAKING — pool_df now returns an envelope:
{"pools": [...], "returned": N, "error": str | None}. A non-null error means the
query failed. (The MCP wrapper already declared @tool_errors("dict"); its return
annotation now matches.)

This is the same defect class found and fixed in minio-aiops 0.3.0, where an
identical except: return [] hid a much larger bug for the life of the tool. A
probe failure must never be presentable as health.