feat(miner): cache policy docs with conditional-GET ETags in discovery (#4842) - #5478

No pull-request evidence was available for contributor 'rust-toml'. GitHub PR search returned zero authored pull requests, zero repositories, and zero activity events. Without hydrated patches or PR metadata, there is no patch-level evidence to review for malicious or backdoored contributions. The heuristic result of 'caution' was generated without code-level inspection and is not actionable. Per instructions, a contributor must not be called safe merely because data is missing. Verdict is inconclusive due to complete lack of evidence.