fix(go): exclude /api/version from parity diff — identity, not contract

/api/version returns each binary's own tag/commit/build_date, which
differs by design between independently built backends. Diffing it
always produces a false positive. Drop it from allRoutes; the route
remains reachable via `make parity ARGS="-route /api/version"`.

Also remove the vestigial `build_meta` allowlist entry (Python returns
the build dict as the top-level response body, not nested under
build_meta, so the scrubber never matched anything).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CHANGELOG.md

@@ -8,7 +8,7 @@
 
 ## 2026-05-07 22:55 CEST — feat(go): M5.4 — parity diff binary + `make parity`
 
-- `go/cmd/parity/main.go`: new standalone binary that GETs `/api/version`, `/api/adults`, `/api/juniors`, `/api/payments` from both Python (:5001) and Go (:8080) backends, scrubs an allowlist (`render_time.total`, `build_meta`), and prints `cmp.Diff` for any remaining differences. Exits 0 on full match, 1 on diffs, 2 on fetch/parse errors — CI-friendly for M7.2.
+- `go/cmd/parity/main.go`: new standalone binary that GETs `/api/adults`, `/api/juniors`, `/api/payments` from both Python (:5001) and Go (:8080) backends, scrubs an allowlist (`render_time.total`), and prints `cmp.Diff` for any remaining differences. Exits 0 on full match, 1 on diffs, 2 on fetch/parse errors — CI-friendly for M7.2. `/api/version` is excluded by design (returns binary identity — tag/commit/build_date — which differs between independently built backends); still accessible via `make parity ARGS="-route /api/version"`.
 - `go/cmd/parity/scrub_test.go`: 4 unit tests covering top-level delete, nested delete, missing path, and non-map parent.
 - `go/go.mod`: `github.com/google/go-cmp` promoted to direct dependency.
 - `Makefile`: `parity` target added (`.PHONY`, help, `cd go && go run ./cmd/parity`).