* docs: restructure documentation by spaces, add Notes and update Math

- Reorganize sidebar by spaces: General, Code, Notes, Math, Tools
- Add Notes Space documentation (Obsidian-like editor)
- Extend Math Notebook docs: currencies, timezones, finance, cooking,
  video/timecode, workdays, rounding, fractions, conditions, and more
- Update storage.md: remove SQLite as engine, keep migration only
- Update sync.md: simplify to markdown vault only
- Update devtools.md: add Generators category
- Update home page: reflect spaces architecture, remove snippet collection
- Remove markdown.md from Code space (moved to Notes)
- Replace all tables with code blocks in math docs for consistency
- Add keyboard shortcuts across all space docs
- Add align-arrows.mjs utility script

* docs: improve website copy and split Notes into separate pages

- Rewrite meta descriptions to reflect full product scope
- Fix grammar and copy across Code documentation
- Split Notes into separate pages with sidebar nav
- Add notes mentions to Storage and Sync pages
- Clean up Math docs, simplify Tools intro
- Fix donate page typo, grammar, tone and CTAs
- Add trust line to download page

* feat: update preview image

* docs: improve Notes documentation formatting and structure

* docs: rewrite documentation tone and structure

* docs: improve homepage features copy

* docs: improve homepage features layout

* docs: add Mermaid notes documentation

* docs: expand JSON visualizer documentation

* docs: update donate label position

* feat: new logo

* docs: update AGENTS.md to reflect current codebase state

* chore: upgrade Node.js from 20.16.0 to 24.14.1

* chore: bump pnpm engines requirement to >=10.0.0

* chore: remove unused marked dependency

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# the commit.

* feat(notes): add internal links parser and cache

* feat(core): add internal link entity lookup and deeplinks

* feat(notes): add internal link editor UI

* fix(notes): defer internal link popup positioning

* fix(notes): align internal link overlays and chips

* fix(api): type internal link entity responses

* feat(notes): add obsidian-style internal links

* fix(notes): handle modifier click navigation

* fix(notes): stabilize internal link interactions

* fix(notes): require modifier key for internal link preview

Preview popover now only appears on Cmd+hover (macOS) or Ctrl+hover
(Win/Linux) instead of plain hover. Supports both hover-then-press
and press-then-hover via document-level key listeners.

* fix(notes): prevent hideMarkup from hiding internal link brackets

The hideMarkup extension was hiding inner brackets of [[Target]] when
the cursor entered from the left, causing a two-step reveal instead
of showing all brackets at once.

* fix(notes): eliminate flicker when navigating to snippets via internal links

Deep link navigation to code space caused flickering because Library.vue's
initApp() raced with openSnippetDeepLink(), briefly showing the previous
selection before the target. Now openSnippetDeepLink() sets
pendingCodeNavigation and isAppLoading before the route change, Library.vue
skips its init when pending, and deep link handles all data loading with
a fallback to default initCodeSpace() on error.

* fix(notes): prevent preview popover from appearing at top-left corner

After navigating to a snippet and returning to notes, the preview
could render at (0,0) because hoveredLink retained a reference to a
detached DOM element. Now destroy() always clears hoveredLink, and
showPreview() checks target.isConnected before reading position.

* feat: add internal link navigation history

* fix: constrain header input with history controls

* fix: reduce internal link preview text size

* fix: use app scrollbar in link preview

* docs: add notes internal links guide

* fix: avoid notes flicker on history back navigation

* fix: reduce internal link preview typography

* feat: refine internal link chip colors

* docs: update image

* feat(devtools): add json diff navigation and assets

* feat(devtools): add json diff state management

* feat(devtools): add json diff interface

* chore(i18n): add russian json diff locale

* feat: persist preferences and devtools menu selection in session

Use sessionStorage to remember the last active menu item in preferences
and devtools views, so navigation state survives within a session but
resets on app restart.

* feat(devtools): scroll sidebar to selected item on mount

* fix(devtools): add bottom padding to sidebar menu

#728)

* feat(notes): add dashboard and force graph

* fix(notes): resolve force graph node ids

* refactor(notes): improve graph visualization

* feat(notes): restyle activity heatmap

* fix(notes): fit activity heatmap to panel

* fix(notes): adapt dashboard to panel width

* fix(notes): use custom dashboard scrollbar

* fix(notes): tighten dashboard widget layout

* fix(notes): keep dashboard pairs on one row

* fix(notes): let heatmap fill available width

* fix(notes): keep stat cards in 2x2 grid

* refactor(notes): remove tag cloud widget

* refactor(notes): make graph interaction more like obsidian

* fix(notes): make graph preview interactive

* fix(notes): preserve circular graph nodes on resize

* refactor(notes): add local graph focus behavior

* fix(notes): keep graph labels readable

* feat(notes): make graph widget fully interactive

* refactor(notes): reuse shared graph scene

* fix(notes): load graph when opening full view

* fix(notes): align graph view header with dashboard

* refactor(ui): reuse shared page header

* refactor(notes): remove redundant graph zoom buttons

* refactor(notes): move graph widget actions into canvas

* refactor(notes): rework graph preview viewport math

* feat(notes): add themed graph and heatmap palettes

* fix(notes): persist selected notes route

* chore: style

* fix(notes): clear graph hover on leave

* fix(notes): improve graph label placement

* fix(notes): preserve graph node position on click

* fix(notes): refresh dashboard on every entry

* refactor(notes): move dashboard entry into sidebar header

* feat(notes): add heatmap activity tooltips

* fix(notes): align graph viewport centering

* refactor(notes): remove manual dashboard refresh actions

* refactor(notes): remove unused graph navigation button from dashboard header

* refactor(notes): clarify dashboard notes limits

* fix(notes): size graph nodes by connectivity

* refactor(notes): align dashboard widget settings labels

* refactor(notes): align graph node colors with connectivity

* fix(notes): clip graph edges to node circles

* fix(notes): soften light graph neighbor states

* fix(notes): tune graph neighbor accent states

* feat(theme): add semantic canvas surface token

* refactor(notes): simplify dashboard card surfaces

* fix(notes): keep route targets in navigation history

* fix(notes): restore UI scroll from navigation history

* fix(notes): keep single folder selection in sync

* fix(notes): reopen selected folder from dashboard