Merge global asset library updates into one PATCH in CLI push
A CLI `push` can update `canvas.asset_library.global` in multiple steps during the same push. One update writes global CSS/JS fields, and a later update writes dependency manifest fields such as `imports`, `assets`, and `shared`.
This is brittle because repeated `PATCH` requests to the same config entity in one `push` can depend on backend behavior around intermediate/staged config state. If a later `PATCH` is applied against an older version of the entity, fields from the earlier `PATCH` can be lost.
Change the CLI push flow to:
1. Build and prepare the global CSS/JS asset library update.
2. Upload dependency artifacts and prepare the manifest update.
3. Send one merged `PATCH` to `canvas.asset_library.global` containing:
* `css`
* `js`
* `imports`
* `assets`
* `shared`
issue