Skip push/PR creation when formatting produces no changes

[Copilot]

The format action was unconditionally committing and pushing (or creating a PR) after running the format command, even when no files were modified — wasting build minutes on a no-op push.

Changes

• format/action.yml: Added a Check for changes step that runs git diff --quiet post-format and sets a detected output
• Both Commit changes and Create Pull Request steps are now gated on steps.changes.outputs.detected == 'true', so neither runs when formatting is already clean

- name: Check for changes
  id: changes
  run: |
    if git diff --quiet; then
      echo "detected=false" >> "$GITHUB_OUTPUT"
    else
      echo "detected=true" >> "$GITHUB_OUTPUT"
    fi
  shell: bash

- name: Commit changes
  if: ${{ inputs.create-pr != 'true' && steps.changes.outputs.detected == 'true' }}
  ...

- name: Create Pull Request
  if: ${{ inputs.create-pr == 'true' && steps.changes.outputs.detected == 'true' }}
  ...