The AI module now prepares for the upcoming retirement of Google's Gemini embedding model by marking it as deprecated. It also adds automatic cleanup that refreshes stored AI embeddings created with deprecated models, helping keep AI features reliable without manual intervention.

The model gemini-embedding-001 will be deprecated soon, so this commit is:
- Deprecating that model.
- Introducing an autovacuum to recompute embeddings that were done using embedding models that have been deprecated.

task-6004597