Expose Windows Job Object CPU accounting

[kreneskyp]

Part of IR-786.

This partial contribution exposes a safe Windows JobObject CPU-time query through the standard-process ChildWrapper API. It reports cumulative user plus kernel time from Job Object accounting, including members that exited before the sample. The Windows integration test exercises a descendant that burns CPU and exits before the parent is sampled.

The resident-memory method fails closed with Unsupported. Windows exposes per-process working-set snapshots, but not a coherent current resident-memory aggregate for a Job Object. This change does not satisfy the resident-memory criterion or complete IR-786.

Checks on macOS:

• cargo fmt --all -- --check passed.
• Windows-target cargo check --tests --target x86_64-pc-windows-msvc --no-default-features --features std,job-object passed (compile only; no Windows tests executed).
• Windows-target Clippy could not complete because rustc could not find the target std; no Clippy pass is claimed.
• cargo test --locked --features std --all-targets passed (55 tests; Windows-only tests were not executed on macOS).
• cargo metadata --no-deps --all-features reports no installable binary targets; cargo package --list does not include a helper binary source.

Native Windows execution and upstream CI remain unverified. This branch is based on main; it may need a rebase after the open kill-on-close PR #64, which touches src/std/job_object.rs.

[passcod]

wtf is "IR-786"

[passcod]

From other PRs by account this appears to be fully-automated AI submissions. Come back with a human touch.