fix(app): remove pluginRoutes prop from Shell component

- Remove pluginRoutes parameter from Shell component signature
- Remove pluginRoutes prop passed to PageLayout
- Remove dashboardItems prop passed to AppDashboard (uses context now)
- Remove unused imports (PluginRoute type, useAppLayout hook)
- Update comment to reflect context-based approach

This completes the migration to context-driven layout slots.

Author: binyamin555

examples/app/src/pages/Shell.tsx

@@ -1,6 +1,6 @@
 import type { PluginHost } from '@react-pkl/core';
-import type { AppContext, PluginRoute } from 'example-sdk';
-import { useAppLayout, AppDashboard } from 'example-sdk';
+import type { AppContext } from 'example-sdk';
+import { AppDashboard } from 'example-sdk';
 import { PageLayout } from '../components/PageLayout.js';
 import { PluginDebugPanel } from '../components/PluginDebugPanel.js';
 
@@ -10,15 +10,13 @@ import { PluginDebugPanel } from '../components/PluginDebugPanel.js';
  * Main landing page that displays the dashboard with plugin-contributed widgets
  * and the plugin debug panel for managing plugins.
  */
-export function Shell({ host, pluginRoutes }: { host: PluginHost<AppContext>; pluginRoutes: Map<string, PluginRoute> }) {
-  const layout = useAppLayout();
-
+export function Shell({ host }: { host: PluginHost<AppContext> }) {
   return (
-    <PageLayout host={host} pluginRoutes={pluginRoutes} currentPath="/">
+    <PageLayout host={host} currentPath="/">
       <h2 style={{ marginTop: 0, color: 'var(--text-primary, inherit)' }}>Dashboard</h2>
 
-      {/* Dashboard - themeable layout slot */}
-      <AppDashboard dashboardItems={layout.dashboard} />
+      {/* Dashboard - themeable layout slot (uses context) */}
+      <AppDashboard />
 
       <PluginDebugPanel host={host} />
     </PageLayout>