test(resolve-target): await rejects.toThrow — missed in bun→vitest migration

vitest requires .rejects.toThrow() to be awaited; bun:test did not.
The missing await at the 404 test caused "expected undefined to be
defined" in CI after PR #997 landed.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

Author: betegon

test/lib/resolve-target.test.ts

@@ -390,7 +390,7 @@ describe("fetchProjectId", () => {
         })
     );
 
-    expect(fetchProjectId("test-org", "test-project")).rejects.toThrow(
+    await expect(fetchProjectId("test-org", "test-project")).rejects.toThrow(
       ResolutionError
     );
   });