chore: migrate contexts to stores and refresh barrel exports

- Move state management from `src/contexts` to `src/stores` (zustand-based)
- Update barrelsby config to include new stores directory
- Add bottom-sheet and auth-background components
- Auto-open browser on dev server ready in VS Code launch config
- Refresh generated barrel index files

barrelsby.json

@@ -2,7 +2,6 @@
   "directory": [
     "./src/data/repositories",
     "./src/data/services/api",
-    "./src/data/services/auth",
     "./src/data/dto/auth",
     "./src/data/dto/chat",
     "./src/data/dto/metrics",
@@ -20,14 +19,14 @@
     "./src/app/chat/components",
     "./src/app/sidebar/components",
     "./src/app/splash/components",
-    "./src/contexts/auth",
-    "./src/contexts/chat",
-    "./src/contexts/sidebar",
-    "./src/contexts/user",
     "./src/hooks",
     "./src/integrations",
     "./src/models/auth",
     "./src/models/chat",
-    "./src/models/user"
+    "./src/models/user",
+    "./src/stores/auth",
+    "./src/stores/chat",
+    "./src/stores/sidebar",
+    "./src/stores/user"
   ]
 }