feat(mcp,cdp): persistent browser contexts for lint_url #157

Job	Run time
Preflight (fmt, clippy, check, agents-md)	38s
MSRV (1.95)	19s
Determinism	44s
cargo-deny	41s
Size guard (<25 MiB)	1m 57s
Test (windows-latest)	3m 8s
Docs (build, no deploy)	31s
Test (macos-latest)	1m 40s
Test (ubuntu-latest)	1m 16s
Coverage	1m 32s
	12m 26s

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