Restructure the notes sidebar with a two-tab header (Notes / Outline)
and relocate the document outline from the editor-side panel into the
sidebar's Outline tab with active heading tracking.
- Add SidebarTabs component with Notes/Outline tabs; Outline disabled
when no note is selected
- Add SidebarOutline component with nested heading hierarchy
(H1→H2→H3), depth indentation, and click-to-scroll
- Add RAF-throttled scroll listener for active heading highlighting
based on scroll position (preview getBoundingClientRect / CM6 viewport)
- Lift headings, scrollToHeading, and activeHeadingIdx state to NotesApp
via EditorPane callback props
- Remove old DocumentOutline component and .doc-outline CSS
- Auto-reset to Notes tab when active note is deleted
- Bump notes package to v0.7.0
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
