feat: confirm playback from the media session, and stop demoting the top row

Phase 3 DoD reached end to end: `artemis run spotify_play query="Rolling
Stones Honky Tonk"` played the right song in 13 steps / 35.3s, with playback
paused first so the pass proves the row tap started it.

Two things stopped it before that, both found on the real phone:

- The playback check asserted on an on-screen "Pause" label that Spotify
  never shows: its transport button keeps the label "Play" while music is
  playing. The recipe now ends with a `playing` step that reads the app's
  media session (state PLAYING) and confirms the track title contains the
  query words. A failure reports the state and the track it found.
- tap_row pressed the wrong row. Once a track is loaded its row carries a
  `Paused` state indicator, and counting that content description as row text
  dropped the top hit below an identical duplicate further down, so the tap
  went to y=1443 instead of y=878. Rows are now scored on their title and
  subtitle only (state lives in content descriptions), and scores within
  rowScoreTolerance are treated as equal so the higher row wins, because
  Spotify already ranks by relevance.

internal/ui/rows_test.go reproduces that results screen, including the state
indicator and the duplicate row.

docs/phase-3-spotify-recipe.md records the successful run, the independent
media-session and audio-output reads, and the failure that preceded it.

README.md

@@ -12,7 +12,7 @@ order.
 |---|---|
 | 1 — Prove the ADB link | ✅ proven — see [`docs/phase-1-adb-link.md`](docs/phase-1-adb-link.md) |
 | 2 — Act primitives | ✅ done — tap by text, type, scroll, back, home, launch |
-| 3 — Spotify recipe | 🟡 built — recipes file, guards, `spotify_play`; the live end-to-end run is still to do, see [`docs/phase-3-spotify-recipe.md`](docs/phase-3-spotify-recipe.md) |
+| 3 — Spotify recipe | ✅ done — `spotify_play` plays the right song end to end (13 steps, 35s), see [`docs/phase-3-spotify-recipe.md`](docs/phase-3-spotify-recipe.md) |
 | 4 — Song radio | not started |
 | 5 — Maps recipe | not started |
 | 6 — Action API | not started |
@@ -86,6 +86,9 @@ file format, the verbs, and why list rows need their own step.
 - **Never touch a locked phone.** A secure keyguard stops Artemis with
   `phone is locked; unlock it and retry`. No PIN is stored, read or typed
   (AGENTS.md section 13 Q2).
+- **Confirm playback from the media session, not the screen.** Spotify's
+  transport button keeps the label "Play" while music plays; the `playing` step
+  asks Android what is actually playing and checks the track title.
 - **Wake first.** Every acting command wakes the screen before it acts (FR-7),
   and it checks the keyguard only after the screen is on.
 - **Bound every command.** No adb call runs without a timeout, and a recipe has