[Feature request] Add theme's modifications to all theme branchs with GitHub Actions

When we add scripts that are useful for all themes, like [ipfs image render](https://github.com/Meta-Network/meta-hexo-starter-custom/blob/main/scripts/ipfs-image-renderer.js), it's best to apply this commit to all or most themes branches. I recommend using a bot like GitHub Actions instead of we do this manually. We can mark a commit as *need to be applied to all themes*, and then let the bot do the work.

Start by reviewing scripts/ipfs-image-renderer.js and the repository's theme branches. Define how a commit is marked for propagation and how GitHub Actions should apply it to all or most theme branches. Done means the workflow reliably performs this propagation without manual copying.

Written by the indexing model from the issue text.