auto-claude: 186-set-default-dark-mode-on-startup (#1656)

* auto-claude: subtask-1-1 - Update DEFAULT_APP_SETTINGS.theme to dark

Change default theme from 'system' to 'dark' so the app starts in dark mode
by default on new installations.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* test: update test to expect dark as default theme

Update the settings:get handler test to expect 'dark' as the
default theme instead of 'system' to match the new default.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

apps/frontend/src/main/__tests__/ipc-handlers.test.ts

@@ -564,7 +564,7 @@ describe("IPC Handlers", { timeout: 30000 }, () => {
 
       expect(result).toHaveProperty("success", true);
       const data = (result as { data: { theme: string } }).data;
-      expect(data).toHaveProperty("theme", "system");
+      expect(data).toHaveProperty("theme", "dark");
     });
   });
 

apps/frontend/src/shared/constants/config.ts

@@ -24,7 +24,7 @@ export const UI_SCALE_STEP = 5;
 // ============================================
 
 export const DEFAULT_APP_SETTINGS = {
-  theme: 'system' as const,
+  theme: 'dark' as const,
   colorTheme: 'default' as const,
   defaultModel: 'opus',
   agentFramework: 'auto-claude',