fix(dashboard): resolve presentCharacters widget styling and auto-layout issues

- Remove double left border accent on character cards by hiding inner border when inside widget container
- Increase maxAutoSize width from 3 to 4 columns to support large displays
- Fix viewport height calculation to use visible area instead of scrollable container height
- Change auto-layout boundary check from > to >= to prevent widgets extending beyond viewport
- Add Done button for cleaner edit mode exit UX
- Wire up Done button event listener in dashboardIntegration

src/systems/dashboard/widgets/presentCharactersWidget.js

@@ -238,7 +238,7 @@ export function registerPresentCharactersWidget(registry, dependencies) {
         category: 'scene',
         minSize: { w: 2, h: 2 },
         defaultSize: { w: 2, h: 3 },
-        maxAutoSize: { w: 3, h: 5 }, // Max size for auto-arrange expansion
+        maxAutoSize: { w: 4, h: 5 }, // Max size for auto-arrange expansion (supports up to 4-col on large displays)
         requiresSchema: false,
 
         render(container, config = {}) {