Allow activate-only launcher use without hako-cmd

[tmori]

Summary

Make activate-only usable for process-only / Core-free launcher configurations without requiring hako-cmd, while preserving the historical hako-cmd preflight for normal activation paths.

This enables configurations such as:

• standalone PDU Bridge
• Web server
• topology aggregator
• other before_start tools

to run with:

python -m hakoniwa_pdu.apps.launcher.hako_launcher launch.json --mode activate-only

without installing Hakoniwa Core or hako-cmd.

Compatibility boundary

The change is intentionally scoped to activate-only.

immediate / normal activate()
  -> prepare hako-cmd first (historical fail-fast behavior preserved)
  -> prepare runtime
  -> start before_start assets
  -> hako-cmd start

activate-only
  -> skip unconditional hako-cmd preflight
  -> prepare runtime
  -> start before_start assets
  -> no hako-cmd start

later cmd(start|stop|reset)
  -> prepare hako-cmd before lifecycle command

LauncherService.activate() keeps require_hako_cmd=True as the default, so direct callers and serve/immediate paths retain the existing behavior. Only the CLI/background activate-only path passes require_hako_cmd=False.

A readiness.type = hako_asset probe still resolves hako-cmd lazily through the existing monitor/provider path.

Existing activate-only users checked

A repository-wide search of the Hakoniwa organization found current activate-only usage in:

• hakoniwa-mujoco-robots
  • tb3-demo.bash
  • tb3-mbody-demo.bash
  • tb3-obstacle-avoidance-demo.bash
• hakoniwa-drone-pro
  • X500 tuning launcher (activate-only is the default)
  • distributed fleet client launcher (activate-only is the default)

The inspected launch files use activate-only to start before_start processes without issuing the simulation start command. Their normal behavior is unchanged when hako-cmd exists.

The one intentional observable difference is failure behavior when hako-cmd is absent:

• before: activate-only failed before starting any process
• after: activate-only may start its before_start processes; hako-cmd is required only if a Hakoniwa lifecycle command or hako_asset readiness probe is actually used

That is the desired Core-free behavior.

Tests

Adds regression coverage that:

• Core-free activation can explicitly skip hako-cmd
• normal activation still performs the historical hako-cmd preflight before starting assets
• lifecycle start still prepares hako-cmd
• background activate-only does not start the simulation and opts out of the preflight

This is needed by the Core-free Zenoh Topology Viewer launcher flow.