feat: add MongoDB support with connection pooling and repository pattern

README.md

@@ -55,12 +55,34 @@ curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
     cargo build
     ```
 
-4.  **Run the application:**
+4.  **Run the application database with Docker (Recommended):**
+    If you have Docker installed
+
+5.  **Run the application (Manual with Docker):**
+    First, start the MongoDB container:
+
+    ```sh
+    docker run \
+      --name mongodb \
+      -p 27017:27017 \
+      -e MONGO_INITDB_ROOT_USERNAME=admin \
+      -e MONGO_INITDB_ROOT_PASSWORD=password123 \
+      -e MONGO_INITDB_DATABASE=purenotify \
+      -v mongodb_data:/data/db \
+      mongo:latest
+    ```
+
+    (Note: The `purenotify` database name here should match `DATABASE_NAME` in your `.env` or `config.rs` for the backend to connect correctly. The `MONGODB_URI` for the backend would be `mongodb://127.0.0.1:27017` or `mongodb://localhost:27017`.)
+
+    Then, run the Rust application:
     For development, you can run the project directly with `cargo run`:
+
     ```sh
     cargo run
     ```
+
     For a release build, run:
+
     ```sh
     cargo run --release
     ```