fix(ci): add workflows:write permission to amber-issue-handler

The amber-handler job fails at the "Push branch to remote" step when
Amber creates or modifies files under .github/workflows/. GitHub
requires the explicit `workflows` permission for any token that
touches workflow files, even if `contents: write` is already granted.

Ref: https://github.com/ambient-code/platform/actions/runs/21777412886/job/62836130769

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

Author: jeremyeder

.github/workflows/amber-issue-handler.yml

@@ -29,7 +29,8 @@ permissions:
   contents: write
   issues: write
   pull-requests: write
-  id-token: write  # Required for OIDC token (Bedrock/Vertex/Foundry/OAuth)
+  id-token: write    # Required for OIDC token (Bedrock/Vertex/Foundry/OAuth)
+  workflows: write   # Required to create/update GitHub Actions workflow files
 
 jobs:
   amber-handler: