fix: getMostRecent relies on array position instead of updatedAt timestamp

[Cheezeiii365]

Summary

ConversationStore.getMostRecent() in packages/main/src/conversationStore.ts uses Array.find() (first positional match) to return the most recent conversation, relying on the implicit invariant that the index array is always sorted newest-first.

Problem

The invariant holds today (create() uses unshift), but updateMeta() can bump updatedAt on an older conversation without re-sorting the array. If a non-newest conversation gets a newer updatedAt, getMostRecent will silently return the wrong entry.

This is a latent bug — not currently triggered in production, but fragile.

Suggested approach

Rather than patching getMostRecent alone, consider re-sorting the index after updateMeta bumps updatedAt, so the "newest-first" invariant remains globally reliable for all consumers.

References

• File: packages/main/src/conversationStore.ts, lines ~144-151
• Related: updateMeta at line ~129, create at line ~104