[codex] Report blocked close-item closeouts

[rickardvh]

Summary

• Add close-item JSON status fields for blocked, closed, dry-run, and no-change outcomes.
• Surface closed, mutation_applied, next_action, and blocked_reason when archive-flow close-item is blocked.
• Cover blocked archive closeout and CLI JSON output in Planning close-item tests.

Root cause

close-item routed execplan ids through archive_execplan, but blocked archive attempts only returned warnings/actions. Automation could miss that the requested close mutation did not happen.

Validation

• uv run pytest packages/planning/tests/test_close_item.py -q
• make test-planning
• make lint-planning
• make typecheck-planning
• uv run python scripts/check/check_planning_surfaces.py

Closes #1216