docs: record the audio clock, and that CI is green

The e2e job passes on both engines for the first time, so the three
files that describe it as red are wrong. Also records the two things
that made it findable: the CI container is reproducible under Docker,
and the app's own audio stack had to be the thing measured.

.planning/plans/active/007-ui-reconciliation.md

@@ -1924,12 +1924,26 @@ route from the albums grid to `track-details`.
 And two things this pass found rather than inherited:
 
 - **Name the dialogs.** One helper, eight call sites.
-- **CI's e2e job cannot go green until the container's audio clock
-  does.** Three specs assert on a position that does not advance
-  there. Either the container gets a sink that really consumes, or
-  those three specs learn to skip when it does not — but silently
-  loosening a tolerance would delete the only assertions this repo has
-  that the player tells the truth.
+
+**CI is green, and the audio clock was the last thing between it and
+green.** Fixed the same pass: `ci.yml` used ALSA's `null` plugin on the
+belief that it paces, and it does not — measured in the CI image
+through beep and oto with `player.InitSpeaker`'s own arguments,
+**3000 ms of audio consumed in 2.96 ms**, against **3762 ms** through a
+PulseAudio null sink. Every track finished instantly, so the position
+reset to zero and three specs failed on a clock that never moved. It
+looked like a flake because `InitSpeaker` succeeds either way, in ~3 ms
+either way. `check` and `e2e` now both pass, **54 specs on Chromium and
+54 on WebKit** — the first fully green run this plan has had.
+
+Two things about how that was found are worth carrying forward. The fix
+was **verified in `ubuntu:24.04` under Docker before it was pushed**,
+including under the private session bus and Xvfb `dev-headless.sh` uses
+— the CI container is reproducible locally, which nothing had tried.
+And the sink is now **checked like the dependency-with-a-rate that it
+is**: a step plays three seconds and fails if they take under two,
+because otherwise the failure surfaces three steps later as "the
+elapsed clock is 19 s adrift" and reads as an app bug.
 
 ## Phase 6 — Explore starts the conversation