Fix: resume coding-agent context rounds

[alphali]

Summary

• resume an existing coding-agent-origin Round from its actual server state
• answer only open_for_agent; route needs_attention to Doable; finalize ready_to_create; monitor creating
• bump the public plugin to 0.2.1 so Cursor, Codex, and Claude Code do not keep the cached workflow

No new state machine or remote transport was added. The helper remains local-only; Doable MCP remains the sole remote authority.

Verification

• npm test — release verification and 2 helper E2E tests passed
• python .../skill-creator/scripts/quick_validate.py plugins/doable-code-context/skills/doable-test-feature — passed
• python .../plugin-creator/scripts/validate_plugin.py plugins/doable-code-context — passed
• claude plugin validate ./plugins/doable-code-context — passed
• git diff --check origin/main...HEAD — passed

Not tested

• No live customer or staging Round was mutated.
• Fresh host reinstall is intentionally left for release verification after review.