feat: 2D editing — floorplan panel, measurements, command palette (v0.3.0)

* sync: port 2D editing features from monorepo (v0.3.0)

## New Features

### Floorplan Panel (7.5K LOC)
- Full 2D editing interface with wall drawing, measurement, and unit display
- Interactive floorplan view with pan/zoom, grid snapping
- Wall thickness visualization, door/window placement
- Zone and slab polygon editing
- Guide image overlay support
- Metric/imperial unit toggle

### Command Palette Overhaul
- Complete rewrite with new command registry system
- Keyboard shortcuts UI with ShortcutToken component
- Editor-specific commands (floorplan, measurements, camera focus)
- Improved search and action organization

### Wall Measurements
- Real-time wall length labels in 3D view
- Metric/imperial conversion
- Wall measurement UI component

### Enhanced Tools
- Wall drafting utilities (grid snapping, validation)
- Node action menu for quick operations
- Improved polygon editing for zones/slabs/sites
- Roof segment panel for granular roof control

## Package Changes

### @pascal-app/core@0.3.0
- New wall-footprint.ts: 2D wall footprint calculation
- Wall mitering exports for floorplan view
- camera-controls:focus event
- Space detection undo pause/resume
- Mark sibling nodes dirty on deletion (miter recalc)

### @pascal-app/viewer@0.3.0
- ErrorBoundary component for robust item rendering
- Broken item fallback UI
- Wall renderer: mark dirty on mount
- Ground occluder: only lowest level punches through
- Unit state (metric/imperial) in viewer store

### @pascal-app/editor@0.1.0
- 48 file changes (16 new, 32 modified)
- New stores: useCommandRegistry, usePaletteViewRegistry
- Tree node drag-and-drop system
- Level selection utilities
- Enhanced scene graph operations

## Apps/Editor
- GeistPixelSquare font for pixel-perfect UI
- Blueprint icon asset
- Updated layout and globals for font support

## Security
- Zero AI imports or internal package refs
- All monorepo-specific code excluded
- Clean audit: no API keys or secrets

## Testing
- Security audit passed ✅
- All AI/internal code excluded ✅
- Version bumps applied ✅

79 files modified, 16 files added
~2600 insertions, ~1400 deletions

* fix: lint cleanup — suppress intentional dep warnings, fix missing dep, remove stale ignores

- Add biome-ignore for 3 intentional useEffect reset patterns (levelId, selectedGuide, selectedId)
- Fix actual missing dependency: currentBuildingId in handleSiteEditShortcutSelect callback
- Remove 3 stale biome-ignore comments in r3f.d.ts (rule not active)

Build and lint pass clean.

* fix: type errors — polygon area guards, selection cast, readonly keywords, door guard

- ceiling-panel, slab-panel, ceiling-tree-node, slab-tree-node, zone-tree-node:
  guard polygon[i]/polygon[j] array access before arithmetic (TS2532)
- scene.ts: introduce toViewerSelection() helper to cast persisted string IDs
  to branded template literal types expected by useViewer.setSelection (TS2345)
- door-panel: guard early return when node is undefined in setSegmentHeightRatio (TS18048)
- editor-commands: remove 'as const' from inline command object, keywords is mutable string[] (TS2322)

All type checks pass. Build and lint clean.

---------

Co-authored-by: Anton Pascal <anton-pascal@users.noreply.github.com>

packages/viewer/src/store/use-viewer.ts

@@ -29,6 +29,9 @@ type ViewerState = {
   theme: 'light' | 'dark'
   setTheme: (theme: 'light' | 'dark') => void
 
+  unit: 'metric' | 'imperial'
+  setUnit: (unit: 'metric' | 'imperial') => void
+
   levelMode: 'stacked' | 'exploded' | 'solo' | 'manual'
   setLevelMode: (mode: 'stacked' | 'exploded' | 'solo' | 'manual') => void
 
@@ -81,6 +84,9 @@ const useViewer = create<ViewerState>()(
       theme: 'light',
       setTheme: (theme) => set({ theme }),
 
+      unit: 'metric',
+      setUnit: (unit) => set({ unit }),
+
       levelMode: 'stacked',
       setLevelMode: (mode) => set({ levelMode: mode }),
 
@@ -187,6 +193,7 @@ const useViewer = create<ViewerState>()(
       partialize: (state) => ({
         cameraMode: state.cameraMode,
         theme: state.theme,
+        unit: state.unit,
         levelMode: state.levelMode,
         wallMode: state.wallMode,
         projectPreferences: state.projectPreferences,