fix: theme switching always defaults to dark mode

Root causes:
1. ThemeProvider was imported but never used in App.tsx and showSetupDialog
2. setThemeConfigCallbacks was never called to inject persistence callbacks
3. Preview/save/cancel theme lifecycle had no provider to coordinate

Changes:
- Export setThemeConfigCallbacks from @anthropic/ink
- Wrap App.tsx children with ThemeProvider (initialState from config, onThemeSave persists)
- Wrap showSetupDialog with ThemeProvider for onboarding/trust dialogs
- Call setThemeConfigCallbacks in init.ts to register load/save callbacks
- Update SnapshotUpdateDialog test to account for new ThemeProvider wrapper

Fixes #theme-switching

src/components/App.tsx

@@ -1,38 +1,36 @@
-import React from 'react'
-import { FpsMetricsProvider } from '../context/fpsMetrics.js'
-import { StatsProvider, type StatsStore } from '../context/stats.js'
-import { type AppState, AppStateProvider } from '../state/AppState.js'
-import { onChangeAppState } from '../state/onChangeAppState.js'
-import type { FpsMetrics } from '../utils/fpsTracker.js'
-import { ThemeProvider } from '@anthropic/ink'
+import React from 'react';
+import { FpsMetricsProvider } from '../context/fpsMetrics.js';
+import { StatsProvider, type StatsStore } from '../context/stats.js';
+import { type AppState, AppStateProvider } from '../state/AppState.js';
+import { onChangeAppState } from '../state/onChangeAppState.js';
+import type { FpsMetrics } from '../utils/fpsTracker.js';
+import { ThemeProvider } from '@anthropic/ink';
+import { getGlobalConfig, saveGlobalConfig } from '../utils/config.js';
 
 type Props = {
-  getFpsMetrics: () => FpsMetrics | undefined
-  stats?: StatsStore
-  initialState: AppState
-  children: React.ReactNode
-}
+  getFpsMetrics: () => FpsMetrics | undefined;
+  stats?: StatsStore;
+  initialState: AppState;
+  children: React.ReactNode;
+};
 
 /**
  * Top-level wrapper for interactive sessions.
  * Provides FPS metrics, stats context, and app state to the component tree.
  */
-export function App({
-  getFpsMetrics,
-  stats,
-  initialState,
-  children,
-}: Props): React.ReactNode {
+export function App({ getFpsMetrics, stats, initialState, children }: Props): React.ReactNode {
   return (
     <FpsMetricsProvider getFpsMetrics={getFpsMetrics}>
       <StatsProvider store={stats}>
-        <AppStateProvider
-          initialState={initialState}
-          onChangeAppState={onChangeAppState}
-        >
-          {children}
+        <AppStateProvider initialState={initialState} onChangeAppState={onChangeAppState}>
+          <ThemeProvider
+            initialState={getGlobalConfig().theme}
+            onThemeSave={setting => saveGlobalConfig(current => ({ ...current, theme: setting }))}
+          >
+            {children}
+          </ThemeProvider>
         </AppStateProvider>
       </StatsProvider>
     </FpsMetricsProvider>
-  )
+  );
 }

src/components/agents/__tests__/SnapshotUpdateDialog.test.tsx

@@ -5,7 +5,10 @@ import { buildMergePrompt, SnapshotUpdateDialog } from '../SnapshotUpdateDialog.
 import { Select } from '../../CustomSelect/index.js';
 
 function getSnapshotDialogFromRenderedTree(rendered: React.ReactElement) {
-  const appStateProvider = rendered as React.ReactElement<{
+  const themeProvider = rendered as React.ReactElement<{
+    children: React.ReactElement;
+  }>;
+  const appStateProvider = themeProvider.props.children as React.ReactElement<{
     children: React.ReactElement;
   }>;
   const keybindingSetup = appStateProvider.props.children as React.ReactElement<{