docs: Add API testing section to README

- Document Bruno API testing collection with organized structure
- Include comprehensive setup and usage instructions
- Add reference to role-based registration restrictions
- Explain admin-only endpoints and authentication requirements

README.md

@@ -50,6 +50,35 @@ nano .env  # or your preferred editor
 - `JWT_SECRET` - Secure random string for JWT authentication
 - `DBPASS` - PostgreSQL database password
 
+### API Testing
+
+The `bruno/` directory contains a comprehensive API testing collection organized into logical subfolders for testing all endpoints:
+
+#### **Collection Structure**
+```
+bruno/user/
+├── auth/                    # Authentication requests
+│   ├── Login User.bru      # POST /api/auth/login
+│   └── Register User.bru   # POST /api/auth/register (with restrictions)
+├── admin/                   # Admin-only management
+│   ├── List Users.bru         # GET /api/auth/users (admin only)
+│   ├── Delete Account.bru       # DELETE /api/auth/account (admin override)
+│   └── Register Admin User.bru # POST /api/auth/register (admin creation)
+└── profile/                  # Profile management
+    ├── Get Profile.bru         # GET /api/auth/profile
+    ├── Update Profile.bru       # PUT /api/auth/profile
+    ├── Update Email.bru         # PUT /api/auth/email
+    ├── Update Password.bru       # PUT /api/auth/password
+    ├── Update Theme.bru         # PUT /api/auth/theme
+    └── Update Username.bru       # PUT /api/auth/username
+```
+
+#### **Usage**
+1. Install Bruno: https://www.usebruno.com/
+2. Import Collection: Open Bruno and import the `bruno/` folder
+3. Select Environment: Choose the "Bookmann" environment
+4. Authentication Flow: Register → Login → Use Bearer token for protected routes
+
 ### Generating Secure Values
 
 **Generate JWT Secret:**