test: raise timeouts for slow integration tests

Two test files were timing out at the default 5s on developer machines,
both pre-existing on origin/main but unrelated to this branch's bug fixes:

- test/gstack-artifacts-init.test.ts: 13 tests spawning real subprocesses
  via fake gh/glab/git shims in PATH. bun's fork+exec overhead pushed
  these past 5s consistently. Added a local test-wrapper that aliases
  test() with a 30s timeout (matches the brain-sync.test.ts pattern
  already in the repo).
- test/gstack-next-version.test.ts: one integration smoke test that
  spawns 'bun run ./bin/gstack-next-version' and parses the resulting
  JSON. The subprocess does a 'gh pr list' against the live GitHub API
  to enumerate claimed version slots. Network latency makes 5s tight;
  raised this single test to 30s.

No production code changed. The tests already passed deterministically
once given enough wall-clock time.

test/gstack-artifacts-init.test.ts

@@ -11,12 +11,18 @@
  * auto-executes (no MCP probe). Per Finding #10: stored URL is HTTPS.
  */
 
-import { describe, test, expect, beforeEach, afterEach } from 'bun:test';
+import { describe, test as _test, expect, beforeEach, afterEach } from 'bun:test';
 import * as fs from 'fs';
 import * as os from 'os';
 import * as path from 'path';
 import { spawnSync } from 'child_process';
 
+// Integration tests spawn real git/gh/glab subprocesses. The default 5s
+// per-test timeout is tight on developer machines; raise to 30s to match
+// the brain-sync.test.ts pattern. The tests stay deterministic (fake bins,
+// no network), but subprocess fork+exec under bun adds non-trivial overhead.
+const test = (name: string, fn: any) => _test(name, fn, 30000);
+
 const ROOT = path.resolve(import.meta.dir, '..');
 const INIT_BIN = path.join(ROOT, 'bin', 'gstack-artifacts-init');