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/web/src/core/environment/index.ts

@@ -0,0 +1,14 @@
+/**
+ * Type-safe Environment Wrapper for apps/web.
+ * DO NOT use `import.meta.env` directly in components. Import this `ENV` object instead.
+ */
+export const ENV = {
+  API_BASE_URL: import.meta.env.VITE_API_BASE_URL || 'http://localhost:8000/api',
+  APP_ENV: (import.meta.env.VITE_APP_ENV || 'development') as 'development' | 'staging' | 'production',
+  IS_PROD: import.meta.env.VITE_APP_ENV === 'production',
+
+  // CouchDB Connection
+  COUCHDB_BASE_URL: import.meta.env.VITE_COUCHDB_BASE_URL || 'http://localhost:5984',
+  COUCHDB_USERNAME: import.meta.env.VITE_COUCHDB_USERNAME || '',
+  COUCHDB_PASSWORD: import.meta.env.VITE_COUCHDB_PASSWORD || '',
+} as const;