Add rate limiting for search

**Problem**
When working with store, the error messages could be more descriptive.

**Suggestion**
Improve error handling and add detailed error messages.

**Context**
This would help with debugging and maintenance.

The issue names no files, tests, or entry points. Start by locating the search implementation and the store error-handling path; clarify the expected rate-limit behavior and error-message details before changing anything, then verify that search requests are limited and failures provide useful debugging information.

Written by the indexing model from the issue text.