feat(core-storage): add PouchEnvelope tests and LocalStorageService implementation

- Introduced tests for PouchEnvelope to validate envelope-aware CRUD operations using an in-memory PouchDB.
- Implemented LocalStorageService with encryption support for sensitive keys, including tests for setItem, getItem, removeItem, and clear methods.
- Defined a generic storage interface (IStorageService) to enforce type-safe serialization/deserialization across storage implementations.

apps/docs-dev/src/packages/core-storage/index.md

@@ -116,7 +116,7 @@ const theme = await appStorage.getItem('THEME'); // Plaintext on disk
 
 ## 🔄 Offline-First Document Storage (PouchDB & CouchDB)
 
-For complex, document-oriented data that requires fault-tolerance, offline support, and bi-directional cloud synchronization, we use the `PouchDatabaseManager`. This layer is powered by [PouchDB](https://pouchdb.com/) syncing to [CouchDB](https://couchdb.apache.org/).
+For complex, document-oriented data that requires fault-tolerance, offline support, and bi-directional cloud synchronization, we use the `PouchDBManager`. This layer is powered by [PouchDB](https://pouchdb.com/) syncing to [CouchDB](https://couchdb.apache.org/).
 
 ### Architecture
 
@@ -134,7 +134,7 @@ graph TD
     end
 
     subgraph CoreStorage ["@repo/core-storage Engine"]
-        MGR[PouchDatabaseManager Factory]
+        MGR[PouchDBManager Factory]
         L_SALES[(Local PouchDB: Sales)]
         L_INV[(Local PouchDB: Inventory)]
     end
@@ -168,13 +168,13 @@ graph TD
 
 ### 1. Initialization (IoC Factory)
 
-The `PouchDatabaseManager` acts as a central singleton. It registers and manages all database instances. If a remote URL is provided, it automatically handles background synchronization.
+The `PouchDBManager` acts as a central singleton. It registers and manages all database instances. If a remote URL is provided, it automatically handles background synchronization.
 
 ```typescript
-import { PouchDatabaseManager } from '@repo/core-storage';
+import { PouchDBManager } from '@repo/core-storage';
 import type { Item } from './types';
 
-export const dbManager = new PouchDatabaseManager();
+export const dbManager = new PouchDBManager();
 
 export const itemDB = dbManager.register<Item>({
   localName: 'items_db',
@@ -184,7 +184,7 @@ export const itemDB = dbManager.register<Item>({
 
 ### 2. CRUD & MongoDB-style Queries
 
-The registered database returns a `PouchDatabaseWrapper`. This wrapper fully abstracts the raw PouchDB API into clean, Promise-based helpers, auto-handling `_rev` conflicts.
+The registered database returns a `PouchService` instance. This wrapper fully abstracts the raw PouchDB API into clean, Promise-based helpers, auto-handling `_rev` conflicts.
 
 | Method | Description |
 |---|---|
@@ -231,6 +231,38 @@ export function InventoryList() {
 }
 ```
 
+### 4. Envelope Pattern (`PouchEnvelopeDBManager`)
+
+If you want to store multiple types of entities (e.g. `items`, `bookings`, `activities`) in a single CouchDB/PouchDB database to simplify sync setup, use the **Envelope Pattern**. 
+
+Instead of `PouchDBManager`, instantiate a `PouchEnvelopeDBManager`. It provides the exact same `PouchService` API (CRUD + Find), but automatically wraps documents into an envelope format internally: `{ _id: "entityName:businessId", entity: "entityName", data: { ... } }`.
+
+```typescript
+import { PouchEnvelopeDBManager } from '@repo/core-storage';
+import type { ItemEntity, BookingEntity } from './types';
+
+export const envelopeDbManager = new PouchEnvelopeDBManager();
+
+// Registers to the SAME database 'master_db', but scoped to 'item'
+export const itemDB = envelopeDbManager.register<ItemEntity>({
+  localName: 'master_db',
+  remoteUrl: 'http://admin:pass@localhost:5984/master_db'
+}, 'item');
+
+// Registers to the SAME database 'master_db', but scoped to 'booking'
+export const bookingDB = envelopeDbManager.register<BookingEntity>({
+  localName: 'master_db',
+  remoteUrl: 'http://admin:pass@localhost:5984/master_db'
+}, 'booking');
+
+// API usage remains identical!
+await itemDB.create({ _id: '123', name: 'Widget' }); // Stored as "item:123"
+const items = await itemDB.getAll(); // Only returns documents where entity === 'item'
+
+// Unique to PouchEnvelopeService: Cross-field keyword searching
+const results = await itemDB.search('widget keyword', ['data.name', 'data.sku']);
+```
+
 ### ✅ Do's and ❌ Don'ts for PouchDB
 
 * **✅ DO use `.onChange()`** to make your UI reactive to background cloud syncs.