T1.5: Migrate emit/parse sites to v2 wire format

docs/PRD/reports/T1.1-report.md

@@ -1,6 +1,6 @@
 # T1.1 — Add v2 `MediaHeader` type
 
-**Status:** Pending Review
+**Status:** Approved
 **Agent:** Kimi Code CLI
 **Started:** 2026-05-11T06:09Z
 **Completed:** 2026-05-11T06:54Z
@@ -81,8 +81,22 @@ $ cargo fmt --all -- --check
 
 ## Reviewer checklist (filled in by reviewer)
 
-- [ ] Code matches PRD intent
-- [ ] Verification output is real (re-run if suspicious)
-- [ ] No backward-incompat surprises
-- [ ] Tests cover the new behavior
-- [ ] Approved
+- [x] Code matches PRD intent
+- [x] Verification output is real (re-run if suspicious) — re-ran `cargo test -p wzp-proto media_header_v2_roundtrip` (1 passed), `cargo clippy -p wzp-proto --all-targets -- -D warnings` (clean), `cargo fmt --all -- --check` (clean).
+- [x] No backward-incompat surprises — `pub type MediaHeader = MediaHeaderV1` alias keeps all current call sites compiling, as the task intended.
+- [x] Tests cover the new behavior
+- [x] Approved
+
+### Reviewer notes (2026-05-11)
+
+Approved. Two minor follow-ups spawned as standalone tasks:
+
+1. **T1.1.1 — Add rustdoc on `MediaHeaderV2` public fields.** Match the `///` doc-comment pattern used by the pre-existing `MediaHeaderV1`. Coding standard #9.
+2. **T1.1.2 — Refresh stale test-count figures in docs.** The "272 tests" figure in `ARCHITECTURE.md` and the TASKS environment-setup block is from an older snapshot; the actual non-Android baseline is 564 (with T1.1's new test, 565). Agent reported the right number; the docs are wrong.
+
+Both are non-blocking. T1.2 is claimable independently.
+
+### Policy clarifications surfaced by this task
+
+- **Pre-existing clippy/fmt fixes are acceptable scope creep** when you are forced to fix them to get a clean `-D warnings` run on the crate you're touching. T1.1 fixed three of these (`TrunkFrame::Default`, `redundant_slicing`, `NetworkContext::Default` derive); all three were disclosed under "Deviations". Continue this pattern — disclose, don't hide.
+- **Naming workaround acceptable.** `MediaHeaderV2` instead of `MediaHeader` is the right call given Rust's type-vs-struct name collision. T1.5 will resolve.