fix(kanban): terminate workers when tasks are blocked or archived

[nankingjing]

Summary

• Terminate host-local kanban worker processes when a task is blocked or archived, reusing the existing _terminate_reclaimed_worker() reclaim path instead of only clearing worker_pid in SQLite.
• Unify block_task() exit so dependency, triage, and blocked routes all terminate workers and fire the lifecycle hook after the write transaction commits.

Fixes #57596

Test plan

• pytest tests/hermes_cli/test_kanban_worker_terminate_on_block_archive.py
• pytest tests/hermes_cli/test_kanban_lifecycle_hooks.py

[alt-glitch]

This was generated by AI during triage.

Duplicate of #31365 — that earlier open PR patches the same hermes_cli/kanban_db.py (block_task + archive_task) via the same _terminate_reclaimed_worker() mechanism, and is the broader superset (also covers done/scheduled manual exits from running). Related: #57596 (the issue this fixes) and #42858 (narrower archive_task-only fix). Maintainer to pick the canonical fix from the cluster.

[nankingjing]

Closing in favor of the earlier canonical fix path that the maintainer review identified in the comment thread.

Per the triage comment on this PR:

• fix(tools): honor plugin web providers in extract/search dispatch #57704: competing approach in the same plugin-web-provider cluster (fix(web_tools): delegate _is_backend_available to provider registry for plugin backends #31829 / fix(tools): honor available plugin extract/search backends in web selection #35327)
• fix(agent): honor custom_providers per-model max_tokens at startup #57548: duplicate of fix(agent): honor custom provider max_tokens #28154 (earliest still-open, broader superset)
• fix(kanban): terminate workers when tasks are blocked or archived #57713: duplicate of fix(kanban): terminate live workers on manual exits from running #31365 (broader superset covering done/scheduled manual exits too)
• fix(state): avoid double-encoding reasoning columns on fork round-trip #57536: duplicate of fix(state,cli,tui-gateway): keep reasoning fields intact across forks and branches #57248 (earlier canonical version with same write-path-only fix)
• fix(gateway): normalize MSYS paths in validate_media_delivery_path #57696: duplicate of fix(gateway): convert MSYS/Git Bash paths in validate_media_delivery_path (#47767) #47821 (earlier canonical MSYS path fix)

Keeping the narrower cluster open does not help the maintainer pick a canonical fix; closing these reduces the supersede noise so the maintainer can land the right one. Thanks to the alt-glitch triage for the cross-references.