test(rules-git): update worktree linked worktree test to expect allowed result

The linked worktree fixture now has its local git config read directly,
so git reset --hard is allowed when the local config is readable and the
git binary is not invoked (or unavailable).

Author: kenryu42

tests/core/rules-git.test.ts

@@ -1311,7 +1311,7 @@ describe('git linked worktree mode', () => {
     chmodSync(fakeGit, 0o755);
     try {
       withEnv({ SAFETY_NET_WORKTREE: '1', PATH: fakeBin }, () => {
-        runGuard('git reset --hard', fixture.linkedWorktree);
+        expect(runGuard('git reset --hard', fixture.linkedWorktree)).toBeNull();
       });
       expect(existsSync(marker)).toBe(false);
     } finally {