docs(01): revise plan 05 wave per checker iteration 1 cascade

Plan 05 depends_on: ["03", "04"], so wave must be max(2, 3)+1 = 4, not 2
(cascade from Plan 04 wave change).

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

.planning/phases/01-stabilize-video-pipeline/01-05-PLAN.md

@@ -2,7 +2,7 @@
 phase: 01-stabilize-video-pipeline
 plan: 05
 type: execute
-wave: 2
+wave: 4
 depends_on: ["03", "04"]
 files_modified:
   - src/background/index.ts