fix(cli): audit-open crashes with ReferenceError: output is not defined (#2236) (#2238)

The audit-open case in gsd-tools.cjs called bare output() on both the --json
and text paths. output is never in scope at the call site — the entire core
module is imported as `const core`, so every other command uses core.output().

Two-part fix:
- Replace output(...) with core.output(...) on both branches
- Pass result (the raw object) on the --json path, not JSON.stringify(result)
  — core.output always calls JSON.stringify internally, so pre-serialising
  caused double-encoding and agents received a string instead of an object

Adds three CLI-level regression tests to milestone-audit.test.cjs that invoke
audit-open through runGsdTools (the same path the agent uses), so a recurrence
at the dispatch layer is caught even if lib-level tests continue to pass.

Closes #2236

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

get-shit-done/bin/gsd-tools.cjs

@@ -781,9 +781,9 @@ async function runCommand(command, args, cwd, raw, defaultValue) {
       const includeRaw = args.includes('--json');
       const result = auditOpenArtifacts(cwd);
       if (includeRaw) {
-        output(JSON.stringify(result, null, 2), raw);
+        core.output(result, raw);
       } else {
-        output(formatAuditReport(result), raw);
+        core.output(formatAuditReport(result), raw);
       }
       break;
     }