docs(01): revise plan 04 wave per checker iteration 1

Plan 04 depends_on: ["02", "03"], so wave must be max(1, 2)+1 = 3, not 1.

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

.planning/phases/01-stabilize-video-pipeline/01-04-PLAN.md

@@ -2,7 +2,7 @@
 phase: 01-stabilize-video-pipeline
 plan: 04
 type: tdd
-wave: 1
+wave: 3
 depends_on: ["02", "03"]
 files_modified:
   - src/offscreen/recorder.ts