v0.2.5 - drift baseline seeded; manifest scoped to no-param endpoints

Commits the first real bairn drift baseline at
discovery/baselines/main/ (me + feed-page1, anonymized
keys-only signatures). The drift-gate stage in CI now diffs
against this baseline on every tag and fails the pipeline if
Famly's response shapes have moved.

Drops /api/v2/relations from the drift manifest: it requires
operator-private ?childId param. Relation shape continues to be
covered by the typed unmarshal in api/famly/me.go on every real
fetch.

No binary behaviour change beyond version reporting.

Posture and conditions of use unchanged: NOTICE.md.