feat: stream Headless progress with resolved identity

[RobertTLange]

What changed

• Stream concise timestamped Headless progress to stderr for normal agent runs.
• Parse Headless JSON traces for final answers, usage, and tool-call summaries across supported agents.
• Label progress as ask[agent-model-reasoning], resolving auto via Headless --print-command and Codex config defaults where available.
• Recover stale/orphaned staged-workspace locks after interrupted runs.

Why

This makes long-running ask calls observable without changing stdout or JSON output, while avoiding stale workspace lock crashes from interrupted runs.

How to test

• npm test
• git diff --check
• npm install -g .