ci: use OIDC for codecov-action
Replace token-based authentication with OIDC (OpenID Connect) for codecov-action.
This is more secure and eliminates the need to manage upload tokens.
Changes:
- Add use_oidc: true to codecov-action configuration
- Add id-token: write permission at workflow level
- Remove token parameter from codecov-action (ignored when using OIDC)
This improves security and follows codecov-action best practices.
Generated by the task: njzjz-bot/njzjz-bot#25.