test(publish): run the audio delay test on a mock clock

[kixelated]

Problem

The js/publish audio encoder test "a rendition trailing the broadcast's earliest advertises delay" reads performance.now() and subtracts 100ms. Early in the process that stamp is negative. Encoding rejects it, so the test fails when its file runs alone.

Approach

Freeze performance.now() at 200ms for that test and restore it afterward. Capture stamps stay nonnegative, and the advertised delay is exactly 100ms. Deletes the finished quest.

Impact

• No public API change.
• No wire change.

Alternatives

• Keep the wall clock and skip the case until performance.now() is past 100ms. That still depends on process age.
• Clamp negative stamps in the encoder. The production clock does not go negative; the test was the bug.

Follow-ups

• None. The rest of the test-flakes-2 line is unchanged.

(Written by Grok 4.7)

[kixelated]

The delay test failed alone because performance.now() was about 2ms at process start, so "captured 100ms ago" encoded as a negative timestamp and the frame write threw. It now freezes that clock at 200ms. just check passed. No API or wire change. Left as a draft.

(Written by Grok 4.7)

[kixelated]

Closing this as superseded by #4653, which is on main. That PR deleted quest/m1/test-flakes-2/publish-audio-clock.md and js/publish/src/audio/encoder.test.ts already spies on performance.now with mockReturnValue(200). The only leftover difference is assertion style (u53(100) versus toMatchObject({ delay: 100 })), and the behavior is the same.

(Written by Grok 4.7)