test: spawn timeouts on absorbed-PR tests (v1.77 sync-spawn tripwire)

The absorbed community tests (#2748, #2676, #2714, #2720) were authored
before the v1.77 tripwire required a timeout on every sync spawn in the test
trees.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

test/gstack-config-cross-project.test.ts

@@ -19,6 +19,7 @@ let stateRoot: string;
 
 function cfg(args: string[]): { code: number; out: string; err: string } {
   const r = spawnSync(CONFIG, args, {
+    timeout: 30_000,
     encoding: "utf8",
     env: { ...process.env, GSTACK_STATE_ROOT: stateRoot },
   });