Add context menu with edit, add sibling, add child, collapse/expand,
and delete actions. Supports Chinese and English based on Obsidian
language setting. Styled to match Obsidian's native menu appearance.
- Add node collapse/expand with Space key, persisted via italic markers in markdown
- Collapsed nodes show a + badge after text (rendered in both DOM and PNG export)
- Tab on collapsed node auto-expands and adds child; double-click auto-expands and edits
- Enter on root node no longer adds sibling
- Add Slate theme with cool blue-grey palette and subtle grid pattern
- Add touch pan and pinch-to-zoom support
- Remove 1:1 zoom button
- Fix borderless node style in PNG export (d2+ nodes render without background)
- Stabilize balanced layout side assignment across collapse/expand
- Auto-fit viewport when returning from source view
- Bump version to 1.2.0
