feat: add README.md for the project (#1)

This commit adds a comprehensive README.md file to the project. The README includes:

- A project description.
- Installation instructions, including dependencies and environment variables.
- Usage instructions.
- Detailed documentation for all API endpoints, including authentication, transactions, and admin routes.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

README.md

@@ -0,0 +1,85 @@
+# Interbend API
+
+Interbend is a Flask-based web application that provides a backend API for managing user balances and transactions. It features a robust authentication system using JWT and includes a separate set of administrative endpoints for system management. The application is designed to be extensible and can be used as a foundation for a variety of financial applications.
+
+## Installation
+
+1.  **Clone the repository:**
+    ```bash
+    git clone https://github.com/your-username/interbend.git
+    cd interbend
+    ```
+
+2.  **Create a virtual environment and activate it:**
+    ```bash
+    python3 -m venv venv
+    source venv/bin/activate
+    ```
+
+3.  **Install the dependencies:**
+    ```bash
+    pip install Flask python-dotenv mysql-connector-python PyJWT
+    ```
+
+4.  **Set up the environment variables:**
+    Create a `.env` file in the root directory of the project and add the following variables:
+    ```
+    JWT_KEY=your_secret_jwt_key
+    JWT_EXPIRATION=30
+    DB_HOST=your_database_host
+    DB_USER=your_database_user
+    DB_PASSWORD=your_database_password
+    DB_NAME=your_database_name
+    ADMIN_KEY=your_secret_admin_key
+    COLLECT_COOLDOWN=30
+    ```
+
+## Usage
+
+To start the application, run the following command in the root directory of the project:
+```bash
+python run.py
+```
+The application will start in debug mode on `http://127.0.0.1:5000`.
+
+## API Endpoints
+
+### Authentication
+
+-   **`POST /register`**: Creates a new user account.
+    -   **Request Body**: `{ "username": "testuser", "email": "test@example.com", "password": "password123" }`
+    -   **Response**: Sets a JWT token in an HTTP-only cookie and returns a success message.
+
+-   **`POST /login`**: Logs in a user.
+    -   **Request Body**: `{ "bid": "your_user_bid", "password": "password123" }`
+    -   **Response**: Sets a JWT token in an HTTP-only cookie and returns a success message.
+
+### Transactions
+
+-   **`GET /balance?bid=<user_bid>`**: Retrieves the balance of a user.
+    -   **Response**: `{ "balance": 100.00 }`
+
+-   **`POST /collect`**: Collects the salary for the authenticated user.
+    -   **Authentication**: JWT token required.
+    -   **Response**: A success message and the new balance.
+
+-   **`POST /transfer`**: Transfers a specified amount from the authenticated user to another user.
+    -   **Authentication**: JWT token required.
+    -   **Request Body**: `{ "to": "recipient_bid", "amount": 50.00, "note": "Payment for services" }`
+    -   **Response**: A success message.
+
+### Admin
+
+All admin endpoints require an admin key in the request body.
+
+-   **`POST /admin/set-job`**: Sets the job for a user.
+    -   **Request Body**: `{ "bid": "user_bid", "job": 1, "key": "your_admin_key" }`
+    -   **Response**: A success message.
+
+-   **`POST /admin/add-money`**: Adds money to a user's account.
+    -   **Request Body**: `{ "bid": "user_bid", "amount": 100.00, "key": "your_admin_key" }`
+    -   **Response**: A success message.
+
+-   **`POST /admin/change-password`**: Changes the password for a user.
+    -   **Request Body**: `{ "bid": "user_bid", "password": "new_password", "key": "your_admin_key" }`
+    -   **Response**: A success message.