fix(agents): handle embedding model dim changes on collection upload (#9365)

Bumps LocalAGI to pick up the LocalRecall postgres backend fix that
resizes the pgvector column when the configured embedding model
returns vectors of a different dimensionality than the existing
collection. Switching the agent pool's embedding model now triggers
a transparent re-embed at startup instead of failing every subsequent
upload with 'expected N dimensions, not M' (SQLSTATE 22000).

Also surfaces a 409 with an actionable message in
UploadToCollectionEndpoint as a safety net for the rare cases the
upstream migration path doesn't cover (e.g. a model swapped at
runtime), instead of the previous opaque 500.