Restrict short queries at API level

[cdrini]

Closes #11271 . Was noticing a good number of these in our solr logs for The or THE or a or * taking 10s+ and hitting the timeout, coming from the search.json api.

Technical

Testing

Put on prod before the second commit, and monitoring performance. No longer seeing these in the logs!

NOTE: This is will prevent some real usecases, like searching for Stephen King's It via the API -- which doesn't time out.

Screenshot

Stakeholders

[Copilot]

Pull Request Overview

This PR adds API-level validation to restrict short search queries (less than 3 characters) and block specific queries like "the" from being processed by the search API. This helps reduce load on the search infrastructure by preventing ineffective or resource-intensive queries.

• Query validation is added to both the legacy web.py endpoint (/search) and the FastAPI endpoint (/search.json)
• Short queries (< 3 characters) and blocked queries return HTTP 422 with descriptive error messages
• Frontend autocomplete logic is updated to use case-insensitive comparison for blocked queries

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
openlibrary/plugins/worksearch/code.py	Adds query validation to the legacy search API endpoint, checking for query length and blocked queries, moves Content-Type header setting before validation
openlibrary/fastapi/search.py	Adds query validation to the FastAPI search endpoint with the same checks for query length and blocked queries
openlibrary/plugins/openlibrary/js/SearchBar.js	Fixes the blocked query check to use case-insensitive comparison, matching the backend behavior

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[RayBB]

This is exactly what we want. I like that we give a nice error too!