* fix: add mistral to MemorySearchSchema provider/fallback unions
The Mistral embedding provider was added to the runtime code but the
Zod config schema was not updated, causing config validation to reject
`provider: "mistral"` and `fallback: "mistral"` as invalid input.
* Changelog: add unreleased note for Mistral memory schema fix
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Co-authored-by: Drake (Moltbot Dev) <drake@clawd.bot>
Co-authored-by: Vincent Koc <vincentkoc@ieee.org>
042947b944