#23414 test(webviews): mark the two 3 s frame-watch windows as fixed waits (base red)

feat-cmux-next is over the fixed-wait baseline. #23374 merged after the ratchet (#23365) had run its CI, and it added a 3 s waitForTimeout to agent-pane-stream-jitter.test.ts and to agent-pane-history-paging.test.ts. Every PR's webviews check now fails on check:fixed-waits.

Both waits are observation windows. Each test records every painted frame for 3 s after the chat opens, then asserts that nothing jumped. The fixed time is what the test measures, so each wait gets a // fixed-wait: marker and the baseline stays where it is.

Verified with bun run check:fixed-waits (992 on the baseline) and scripts/web-lint.sh. The change is comments only.

Agent session: huge-blue

🤖 Generated with Claude Code

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Summary by cubic

Marks the two 3-second frame-watch windows in the webviews tests as fixed waits so check:fixed-waits passes again on the baseline.

#23374 added the waits after the fixed-wait ratchet (#23365) had run CI, putting feat-cmux-next over its baseline. Both waits are observation windows: each test records painted frames for 3 s after the chat opens and asserts no jumps, so the fixed time is what the test measures. The change adds // fixed-wait: markers to both waits and is comments only.