chore(channels): make plugin-example private and remove from release workflow

- Mark @qwen-code/channel-plugin-example as private in package.json
- Remove publish step from release workflow
- Remove file: to semver rewrite logic in version script
- Use file: reference for @qwen-code/channel-base dependency

This change prevents the example plugin from being published to npm, as it's only intended for internal/development use.

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

.github/workflows/release.yml

@@ -207,13 +207,6 @@ jobs:
         env:
           NODE_AUTH_TOKEN: '${{ secrets.NPM_TOKEN }}'
 
-      - name: 'Publish @qwen-code/channel-plugin-example'
-        working-directory: 'packages/channels/plugin-example'
-        run: |-
-          npm publish --access public --tag=${{ steps.version.outputs.NPM_TAG }} ${{ steps.vars.outputs.is_dry_run == 'true' && '--dry-run' || '' }}
-        env:
-          NODE_AUTH_TOKEN: '${{ secrets.NPM_TOKEN }}'
-
       - name: 'Create GitHub Release and Tag'
         if: |-
           ${{ steps.vars.outputs.is_dry_run == 'false' }}