Release TaskNotes 4.13.0

[callumalpass]

Summary

• Prepare 4.13.0 version metadata and versioned release notes; reset unreleased notes.
• Put the API/MCP authentication migration notice first.
• Include the previously local release-announcement commit, update its stable-version wording and link to the current v5 beta.

Validation

• 712 Jest suites / 4,232 tests pass; 70 suites / 1,011 tests skipped, four todo.
• Full lint, i18n verification (all eight translated locales 2240/2240), production/test build and full documentation checks pass.
• Native Obsidian: recurrence editor and completion, Reading-mode scrolling with visible/hidden properties, synthetic localhost OAuth and release-note rendering checked.
• Real mobile-device and real provider-login acceptance unavailable: no attached device or configured test credentials. No claim that these were verified.

Publication

After CI and merge, tag 4.13.0, verify the workflow-built draft artifacts and attestations, then publish as latest stable. Keep diagnostic-only issues open and perform scoped issue closeouts only after publication.