2026.7.6-canary.1033

feat(core): onenote importer (#15198)

#### PR Dependency Tree


* **PR #15198** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Added OneNote import support for `.one`, `.onetoc2`, and `.onepkg`,
including OneNote-to-markdown content conversion.
* OneNote now appears in the import flow with a dedicated label and
format tooltip, and file pickers recognize the new OneNote type.

* **Bug Fixes**
* Import options that are desktop-only are now disabled when not running
in the desktop app, with clear messaging.
* Improved imported asset handling by converting non-image embedded
assets into attachments for more consistent results.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->