Place T3 control and workload processes in verified CPU roles

[Mjones13]

Adds opt-in Linux CPU placement so the T3 control process and launched workloads can enter verified cgroup roles before payload execution. The helper verifies immutable bindings and group identity, and required placement fails closed. Launcher replacement, shared spawning, both PTYs, Claude SDK launches and telemetry use the same placement contract; an absent configuration preserves existing behavior.

Source is synchronized with canonical main e1f3015 through ordinary merge 728a8a9. PR #5 covers unrelated sidebar inventory; it supplies no dependency.

Validation: current merged candidate passed 199 tests across 12 placement/usage files, 163 NativeTelemetryClient/server tests, and server typecheck. Original placement source additionally passed targeted lint, native bundle compilation and five native-build lifecycle checks on each declared Node engine floor. Those build checks remain bound to d58857e; no unchanged native build was repeated.

This PR publishes source only. No shared service, scheduler, cgroup or release was activated. Repository package version 0.0.38 differs from live 0.0.46-nightly.20261003.2638; activation requires the owning release process to reconcile exact installed source, runtime closure, CPU delegation and a separately approved cold window. Positive native placement and response improvement remain unproved.

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[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.6 KiB	13.5 KiB	−29 B (−0.2%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.0 KiB	7.0 KiB	−6 B (−0.1%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.5 KiB	6.5 KiB	−23 B (−0.3%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	57.0 KiB	57.0 KiB	−44 B (−0.1%)	66.4 KiB	✅
Codex	Live turn messages	9	8	−1 (−11.1%)	21	✅
Claude	Total thread wire	13.6 KiB	13.6 KiB	−16 B (−0.1%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.0 KiB	7.0 KiB	+1 B (+0.0%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.5 KiB	6.5 KiB	−17 B (−0.3%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.8 KiB	57.8 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	9	9	0 (0.0%)	21	✅

Baseline: e1f3015 · PR result: 728a8a9 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 113.8 KiB
• Claude decoded thread snapshot: 114.5 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.