fix(http): mint the fresh request id through randomId

The proxy no longer calls crypto.randomUUID itself, so it leaves the
client-random-id exemption list; the request-id helper uses the shared
randomId, which also works without a secure context.

src/__tests__/client-random-id-guard.test.ts

@@ -47,8 +47,6 @@ const SKIP_DIRS = new Set([
  * runs on the server where the property always exists.
  */
 const SERVER_SIDE_EXEMPT = new Set([
-  // Next middleware — runs on the edge runtime, never in the page.
-  "src/proxy.ts",
   // The one module allowed to reach for the platform call.
   "src/lib/random-id.ts",
 ]);