test(release): validate only the selected preflight job

Scope the steps schema to the release job whose preflight is executed, allowing unrelated reusable-workflow jobs such as qualification. Preserve all four valid and invalid metadata execution checks.

Reproduced on main ec3db3745: 35 passed, 4 failed. After the fix: 104 release and CI boundary tests pass; check:fast and format:check pass.

tests/boundary/filesystem/releaseCheckpoint.test.ts

@@ -649,9 +649,8 @@ it.skipIf(process.platform === "win32").each([
     const sourceSha = await candidate(f, valid ? "6.0.0" : "5.1.0");
     const workflow = z
       .object({
-        jobs: z.record(
-          z.string(),
-          z.object({
+        jobs: z.object({
+          [job]: z.object({
             steps: z.array(
               z.object({
                 name: z.string().optional(),
@@ -659,7 +658,7 @@ it.skipIf(process.platform === "win32").each([
               }),
             ),
           }),
-        ),
+        }),
       })
       .parse(
         parse(