* fix: resolve MeiliSearch startup sync failure from model loading order
`indexSync.js` captures `mongoose.models.Message` and
`mongoose.models.Conversation` at module load time (lines 9-10).
Since PR #11830 moved model registration into `createModels()`,
these references are always `undefined` because `require('./indexSync')`
ran before `createModels(mongoose)` in `api/db/index.js`.
Move the `require('./indexSync')` below `createModels(mongoose)` so
Mongoose models are registered before `indexSync.js` captures them.
* fix: defer model lookups in indexSync, add load-order regression test
- Move mongoose.models.Message and mongoose.models.Conversation lookups
from module-level into performSync() and the indexSync() catch block,
eliminating the fragile load-order dependency that caused the original
regression
- Add guard assertion that throws a clear error if models are missing
- Add comment in api/db/index.js documenting the createModels ordering
constraint
- Add api/db/index.spec.js regression test to prevent future re-introduction
of the load-order bug
* fix: strengthen regression test to verify call order, add guard in setTimeout path
- Rewrite index.spec.js to track call sequence via callOrder array,
ensuring createModels executes before indexSync module loads
(verified: test fails if order is reversed)
- Add missing model guard assertion in the setTimeout fallback path
in indexSync.js for consistency with performSync
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Co-authored-by: Danny Avila <danny@librechat.ai>
