fix(gateway): scrub worker scope from Windows root launches

[texasich]

Summary

• remove delegated/Kanban worker ownership markers from generated Windows gateway CMD and VBS launchers
• apply the same isolation to direct detached gateway spawning and the post-update restart watcher
• source the marker set from agent.delegation_context so launcher behavior follows the existing ownership authority

Problem

A Windows root gateway can be launched by a process that is currently operating as a delegated child or Kanban worker. The generated launchers, direct detached spawn path, and post-update restart watcher previously inherited those ownership markers unchanged.

The new root gateway could therefore misidentify itself as the parent worker instead of establishing a fresh root process boundary.

A harmless-child probe against current main observed all ten seeded ownership markers in both generated launcher children. The same probe against this change observed none of them while preserving HERMES_HOME and an unrelated sentinel variable.

Changes

• define the Windows root-gateway ownership marker set from DELEGATED_CHILD_ENV_MARKER, KANBAN_ENV_KEYS, and the two legacy Kanban branch/worktree markers
• clear those markers before generated CMD and VBS launchers start Python
• add root_gateway_subprocess_env(), which applies the normal gateway overlay and then removes ownership markers
• use the helper in _spawn_detached()
• give the Windows post-update restart watcher a scrubbed environment in both its primary launch and no-breakaway fallback
• add native-Windows regression coverage for CMD, VBS, direct spawn, and restart-watcher behavior

Verification

• tests/hermes_cli/test_gateway_windows.py: 11 passed
• tests/hermes_cli/test_gateway.py: 10 passed, 5 skipped
• tests/hermes_cli/test_update_gateway_launcher_refresh.py: 2 passed
• related Windows-native gateway tests: 12 passed
• native CMD/VBS harmless-child probe: passed
• Ruff: passed
• git diff --check: passed
• Windows footgun scan: passed

Scope

• Windows automated gateway launch and relaunch paths only
• no Scheduled Task ACL changes
• no POSIX behavior change
• manually invoking foreground hermes gateway run from inside a worker shell remains outside this change

[alt-glitch]

This was generated by AI during triage.

Related to #70809, #70898, and #81843: this covers the distinct Windows root-gateway launcher and restart boundary in the broader inherited-worker-scope family.