style: fix ci.yml indentation to standard 2-space YAML formatting

The previous commit introduced broken indentation (up to 1400+ spaces deep).
This reformats the file with standard 2-space YAML indentation matching the
project style, without changing any workflow content or logic.

https://claude.ai/code/session_01U7QjdwKAp3D2Qx4ifntWk5

Author: claude