Allow either hand at the commit, and measure continuous redraws

Committing from the agent rules out running it where there is no git
identity, a sandbox included. Either is now fine: commit on the user's
word where the setup allows it, or write the message and hand it over.

Redrawing continuously is the other addition. A level meter reported a
fresh value every animation frame, so its whole menu reconciled sixty
times a second, silence included, and nobody noticed until review. A PR
that adds anything of the kind now says what it costs, or better, counts
the redraws — commits rather than render calls, since React runs a
component it then discards.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/agents/testing.md

@@ -12,6 +12,8 @@ lines a PR touches.
 - Reuse the factories in `src/utils/test.ts` — `mockRemoteParticipant`,
   `mockMatrixRoom`, `mockLivekitRoom`, `MockRTCSession`. Hand-rolled mocks drift.
 - Snapshots live in `__snapshots__/`; update with `pnpm test <Name> -u`.
+- How often something redraws is testable: drive the frames and count commits, not
+  render calls. An effect with no dependency array runs once per commit.
 - `component/**/*.test.ts` runs in the same jsdom project as `src`.
 
 ## Storybook