Closes #2029

Summary

Pasting a single HTTP(S) URL over selected text in the WYSIWYG editor now keeps that text as the link label. For example, selecting bar in foo bar foo and pasting https://home.com produces foo [bar](https://home.com) foo.

The change supports safe inline selections in paragraphs, headings, lists, quotes, and individual table cells. Plain-text paste still replaces the selection. Code, existing links/images/math, cross-block selections, and partially selected formatting keep their existing paste behavior. One undo restores both the original text and selection.

Type of change

• Bug fix (non-breaking, fixes an issue)

Test plan

• Added Muya integration coverage for URL validation, rich clipboard HTML, reverse selections, Unicode, formatting, escaping, table cells, and fallback behavior.
• 212 clipboard/history unit tests pass.
• 3 Chromium E2E tests pass, including native plain/HTML clipboard paste, caret position, undo/redo, selection restoration, and plain-text paste.
• Muya lint, typecheck, and circular dependency checks pass (lint warnings remain).
• Root lint and desktop typecheck pass (existing lint warnings remain).
• Tested on macOS.

Notes for reviewers

Page-title fetching is a separate follow-up. This PR preserves the selection before that existing pipeline runs and does not add an Electron dependency to Muya.

By submitting this pull request, I confirm that my contribution is made under the terms of the MIT license.