e2b293f41c
robots.txt is a domain-level document and does not vary by session. Keying the cache by (domain, sid) was both wasteful and incorrect — it caused redundant fetches when the same domain was accessed by different sessions. - Cache is now keyed by domain string only; all sessions share one entry - Removed asyncio.Event inflight-deduplication mechanism (superseded by the prefetch approach added in the next commit) - clear_cache() loses the `sid` parameter (breaking change); clearing a domain now evicts the single shared entry for all sessions - Updated tests to reflect shared-cache semantics Files: scrapling/spiders/robotstxt.py, tests/spiders/test_robotstxt.py