refactor: restructure storage and environment modules; remove unused code

- Deleted unused PouchDB configuration and types from core storage.
- Removed Electron-related hooks and utilities that are no longer needed.
- Introduced new local storage management for application keys.
- Created a new environment wrapper for landing application.
- Added public HTTP client for landing application with minimal configuration.
- Implemented new PouchDB entities for items and POS configurations.
- Updated main application entry point to reflect new storage structure.

apps/landing/src/core/environment/env.ts

@@ -0,0 +1,6 @@
+/**
+ * Type-safe Environment Wrapper for apps/landing.
+ */
+export const ENV = {
+  CMS_API_URL: import.meta.env.VITE_CMS_API_URL || 'http://localhost:8001/cms',
+} as const;