Add rate limiting for search

**Description**
Currently middleware lacks proper caching support.

**Proposed solution**
Add configurable caching with sensible defaults.

**Priority**: Low/Medium

No files or tests are named. Start by locating the search entry point and middleware/configuration handling, then resolve whether the intended scope is rate limiting, caching, or both. Done should include agreed configuration behavior, sensible defaults, and tests covering the resulting limits or cache behavior.

Written by the indexing model from the issue text.