[Yana OS] Add automatic scheduler and cross-platform process supervisor

[yanacuti1121]

Context

Yana now has durable action intents and native system-health sampling, but it does not yet have an authoritative scheduler or cross-platform process supervisor.

Objective

Run approved automatic work without requiring the user to invoke a command for every cycle, while preserving truthful process lifecycle and resource boundaries.

Scope

• Add an explicit one-time service installation flow followed by automatic operation.
• Define scheduler cadence, wake-up, backoff, and single-worker ownership.
• Define process-tree behavior for macOS, Linux, and Windows.
• Track PID/process identity without claiming liveness from stale metadata.
• Forward cancellation and shutdown signals.
• Recover actions left running after worker crash.
• Integrate resource-policy preflight before process launch.

Platform contract

• macOS: launchd-compatible service and process-group semantics.
• Linux: systemd user service/timer and cgroup-v2 evidence where available.
• Windows: Task Scheduler/service entry and Job Object semantics.

Acceptance criteria

• Only one worker claims a given project queue.
• Restarting the service does not duplicate action execution.
• SIGTERM/stop requests reach the active process tree.
• SIGKILL/crash releases locks and produces recoverable state.
• Orphaned descendants are detected and reported truthfully.
• Install/status/uninstall paths are documented and tested per platform.
• No service installation happens silently during package installation.

Dependencies

• Typed autonomy executor issue.
• PR feat(os): add native system health monitoring #165 system-health service patterns.

Attribution

Roadmap owner: Vũ Văn Tâm. Initial issue structure: OpenAI Codex.