chore(claude-commands): add /radio + /rewind, refine /clear /review /context signatures, bump to v2.1.138

Insert /radio under Config tag (#12) — opens Claude FM lo-fi radio in browser,
prints stream URL when no browser is available; not on Bedrock/Vertex/Foundry.
Add /rewind under Session tag (#76) — checkpointing alias for /checkpoint and
/undo. Update three signatures with optional arguments: /clear → /clear [name]
(label previous conversation in /resume picker), /review → /review [PR]
(accept optional PR), /context → /context [all] (expand per-item breakdown).
Total grows 75 → 76 with renumbering. Badge to v2.1.138 / May 09 2026 6:58 PM
PKT.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: shanraisshan