ci: Add converted-to-draft label to enforce-draft workflow

Adds a label to PRs that were auto-converted to draft, enabling
maintainers to filter and track how often the rule is violated.

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

Author: stephanie-anderson

.github/workflows/enforce-draft-pr.yml

@@ -38,6 +38,13 @@ jobs:
               return;
             }
 
+            // Label the PR so maintainers can filter/track violations
+            await github.rest.issues.addLabels({
+              ...repo,
+              issue_number: pullRequest.number,
+              labels: ['converted-to-draft'],
+            });
+
             // Check for existing bot comment to avoid duplicates on reopen
             const comments = await github.rest.issues.listComments({
               ...repo,