fix(node): throw for child_process sync failures

[andrewtdiz]

Summary

• Fixes node:child_process — execSync/execFileSync do not throw on non-zero exit #1938 by making child_process.execSync and execFileSync throw when the child exits non-zero.
• Captures the child pid while waiting so the thrown Error-like value exposes enumerable status, signal, output, pid, stdout, and stderr fields.
• Adds a focused node-suite/child_process/sync/nonzero-throw parity fixture covering success paths, stderr capture, execFileSync args, and both sync failure helpers.

Verification

• Baseline before fix: PERRY_NO_CACHE=1 ./run_parity_tests.sh --suite node-suite --module child_process --filter nonzero-throw failed because Perry printed execSync no throw: out where Node entered catch.
• PERRY_NO_CACHE=1 ./run_parity_tests.sh --suite node-suite --module child_process --filter nonzero-throw PASS.
• PERRY_NO_CACHE=1 ./run_parity_tests.sh --suite node-suite --module child_process PASS 1/1.
• PERRY_NO_CACHE=1 ./run_parity_tests.sh --filter test_parity_child_process PASS.
• cargo test -p perry-runtime child_process --lib PASS with pre-existing warnings.
• cargo fmt --all -- --check PASS.
• jq empty test-parity/known_failures.json PASS.
• git diff --check PASS.

Non-goals

• Default Buffer stdout/stderr or encoding option parity (node:child_process — exec/execFile/sync ignore the encoding option (no Buffer stdout/stderr) #1937).
• spawnSync result expansion (node:child_process — spawnSync result missing pid/signal/output/error fields #1936).
• Async exec/execFile failure Error shape (node:child_process — exec/execFile failure Error missing .code/.signal/.killed/.cmd #1935).
• Streaming subprocess IO, kill behavior, IPC/fork, timeout handling, spawn failure errors, or full signal-name parity.