Resolve local worker policy from the Blob URL creator environment, including
meta updates delivered before startup. Keep existing worker snapshots and
SharedWorker reuse stable, and carry the policy through worker-created URLs.
Preserve parent request and child response policy for nested HTTP workers.
Validate with the complete fmt, clippy, and nextest gates (20,458 passed),
73 original WPT files (665 -> 667 passed, zero regressions), and 226 network
comparisons covering worker types, ownership, policy timing, and overrides.