Restore automated push-triggered CI and release workflows

[chenrui333]

Push-triggered workflows are not firing in this repository, even though Actions are enabled and the workflows are active.

Evidence:

• gh api repos/chenrui333/kafka-gitops/actions/permissions returns enabled: true
• gh api repos/chenrui333/kafka-gitops/actions/runs?event=push&per_page=20 returns total_count: 0
• Java CI can be run manually, and Release can be run via workflow_dispatch, but regular push and tag-push automation did not fire
• Pushing tag 0.3.0 did not create a release run automatically

Expected:

• branch pushes trigger gradle.yml
• tag pushes trigger release.yml automatically

This may require repo-level investigation in addition to workflow YAML cleanup.

[chenrui333]

Additional investigation results:\n\n- The repository is not a fork (gh repo view --json isFork,parent shows isFork: false).\n- Actions are enabled and allow all actions (gh api repos/chenrui333/kafka-gitops/actions/permissions).\n- Workflow permissions are write (gh api repos/chenrui333/kafka-gitops/actions/permissions/workflow).\n- The repo event stream shows normal PushEvent activity on refs/heads/main.\n- Re-disabling and re-enabling both gradle.yml and release.yml did not restore automation.\n- Pushing a temporary branch ref (push-trigger-smoke-20260323-2233) also did not create any push workflow runs.\n\nCurrent conclusion: this does not look like a simple workflow YAML problem. The remaining problem is likely repo-side or GitHub-side workflow trigger behavior that needs separate investigation.