lock iter1 acceptance criterion: before/after screenshot anchor

Operator decision 2026-05-08: the iter1 fix is shipped only when frame
10 of the bbb fixture under --vo=dmabuf-wayland matches the expected
reference (captured via --vo=gpu on same hardware/session).

- screenshots/frame10_dmabuf_green.png — current broken state
- screenshots/frame10_expected.png — target post-fix state
- screenshots/README.md — verification protocol (SSIM > 0.95 + valid
  WAYLAND_DEBUG .add() semantics + no regression on vo=gpu / vo=wlshm)
- phase0_findings.md — references the criterion in the conclusion section

This locks the campaign's deliverable. Patches that change wire-protocol
.add() shape but don't restore the picture do not satisfy iter1.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

phase0_findings.md

@@ -54,6 +54,10 @@ mpv --hwdec=v4l2request --vo=gpu fourier-test/bbb_1080p30_h264.mp4
 
 Correct picture, slow due to GPU shader path on Mali-G52. Documented as the campaign's interim recommended path.
 
+**Locked acceptance criterion for iter1 (2026-05-08):**
+
+Per operator decision, the iter1 fix is considered shipped only when the before/after screenshot pair in `screenshots/` reconciles. The current broken state is `screenshots/frame10_dmabuf_green.png` (uniform dark green). The target post-fix state is `screenshots/frame10_expected.png` (correct bbb frame 10, captured via the working `--vo=gpu` path on the same hardware/session). Verification protocol in `screenshots/README.md` — SSIM > 0.95 on the central frame area + valid `.add()` semantics in WAYLAND_DEBUG capture + no regression on `--vo=gpu` or `--vo=wlshm`.
+
 ---
 
 ## Locked research question (original — superseded by Phase 0 conclusion above)