#22837 Wake receiver deadlines on macOS

Adds a macOS continuous timer to receiver waits and HTTP cancellation. It uses the captured elapsed budget and shared readiness checks, so idle waits can expire across sleep.

Mac verification passed 145 receiver tests and target lint at 2b8b085766e; the wakeup regression failed before the fix. Linux passed 171 receiver tests, all 14 privileged process controls, lint and Rust 1.91 checks. Live sleep and provider capture/restore remain unverified.

Changelog

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