* fix(threads): clean up local thread data after thread deletion
Delete DeerFlow-managed thread directories after the web UI removes a LangGraph thread.
This keeps local thread data in sync with conversation deletion and adds regression coverage for the cleanup flow.
* fix(threads): address thread cleanup review feedback
Encode thread cleanup URLs in the web client, keep cache updates explicit when no thread search data is cached, and return a generic 500 response from the cleanup endpoint while documenting the sanitized error behavior.
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Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
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