feat(dashboard): implement smart widget scaling and improved auto-layout

- Add resetWidgetSizesToDefault() to reset all widgets to default sizes before auto-arrange/reset
- Implement continuous expansion algorithm that fills available space up to maxAutoSize limits
- Add visible height detection to prevent widgets expanding beyond viewport (no forced scroll)
- Update all widget defaultSize and maxAutoSize for optimal 1x1 compact layouts
  - Info widgets (calendar, weather, temp, clock): 1x1 default, 1x2 max
  - Location: 2x2 max (was 3x3)
  - Characters: 3x5 max, moved to 'scene' category (eliminates Social tab)
  - User Info: 2x1 max (prevents expansion)
  - User Mood: 1x1 default and max (compact top-right placement)
  - User Attributes: 3x5 max (fills bottom space)
  - User Stats: 3x3 max
- Fix CSS scaling for 1x1 widgets
  - Replace viewport-based units with fixed rem values
  - Reduce icon/graphic sizes to fit with visible text
  - Add explicit gaps and padding for consistent spacing
  - Set line-height: 1 to prevent text overflow
- Reorganize default layout
  - Status tab: User Info (2x1) + Mood (1x1 top right) + Stats + Attributes
  - Scene tab: Info widgets (1x1) + Location + Characters (all on one tab)
  - Inventory tab: Full inventory widget

Auto-arrange and reset now properly size widgets to defaults and expand to fill
available space without exceeding visible area.

src/systems/dashboard/widgets/userStatsWidget.js

@@ -34,6 +34,7 @@ export function registerUserStatsWidget(registry, dependencies) {
         category: 'user',
         minSize: { w: 1, h: 2 },
         defaultSize: { w: 2, h: 2 },
+        maxAutoSize: { w: 3, h: 3 }, // Max size for auto-arrange expansion
         requiresSchema: false,
 
         /**