fix(test): catch leftover birthYear 2000 defaults in helpers

cbd74ea sed missed two `??` default-fallback patterns:
- e2e/golden-paths.spec.ts:31 `birthYear: opts.birthYear ?? 2000`
- e2e/production-ready.spec.ts:38 `birthYear: opts.birthYear ?? 2000`

These are the per-spec `register(page, opts)` helpers; specs that
called them without an explicit birthYear got the 2000 default,
which the post-G-01 server clamp rejects with `Too small: expected
number to be >=2010`. CI v3 surfaced this on every `gp_...` and
`pr_...` registration.

Both swapped to 2012 (within the 7-16 GDPR-K target band) — same
fix as the other fixture sites.

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

Author: B2JK-Industry

e2e/golden-paths.spec.ts

@@ -28,7 +28,7 @@ async function register(
     data: {
       username,
       password: "correct horse battery 1",
-      birthYear: opts.birthYear ?? 2000,
+      birthYear: opts.birthYear ?? 2012,
     },
   });
   expect(r.ok(), `register ${username}: ${r.status()} ${await r.text()}`).toBeTruthy();

e2e/production-ready.spec.ts

@@ -35,7 +35,7 @@ async function registerFresh(
     data: {
       username,
       password: "correct horse battery 1",
-      birthYear: opts.birthYear ?? 2000,
+      birthYear: opts.birthYear ?? 2012,
       ...(opts.parentEmail ? { parentEmail: opts.parentEmail } : {}),
     },
   });