docs: update npm commands to bun in README and documentation files

- Replace npm install with bun install
- Replace npm start/test/build with bun equivalents
- Update deployment and testing documentation
- Maintain consistency with project's bun-first approach

🤖 Generated with [AI Assistant]

Co-Authored-By: AI Assistant <noreply@ai-assistant.com>

CLAUDE.md

@@ -24,10 +24,10 @@ After implementing any feature, fix, or update, you MUST:
 1. **Build and test** the changes:
    ```bash
    # Backend
-   cd backend && npm test
+   cd backend && bun test
 
    # Frontend
-   cd frontend && npm run build
+   cd frontend && bun run build
    ```
 
 2. **Create a git commit** with a descriptive message:
@@ -99,19 +99,19 @@ Frontend proxies API requests to `http://localhost:5000` in development.
 ### Backend
 ```bash
 cd backend
-npm install
+bun install
 # Create .env file with MONGO_URI, JWT_SECRET, PORT
 node server.js  # Start backend on port 5000
-npx eslint .    # Run linter
+bunx eslint .    # Run linter
 ```
 
 ### Frontend
 ```bash
 cd frontend
-npm install
-npm start       # Start dev server on port 3000
-npm test        # Run tests in watch mode
-npm run build   # Production build
+bun install
+bun start       # Start dev server on port 3000
+bun test        # Run tests in watch mode
+bun run build   # Production build
 ```
 
 ## Environment Variables
@@ -185,16 +185,16 @@ Comprehensive test infrastructure is in place for both backend and frontend.
 Backend:
 ```bash
 cd backend
-npm test              # Run all tests
-npm run test:coverage # Run with coverage report
-npm run test:watch    # Run in watch mode
+bun test              # Run all tests
+bun run test:coverage # Run with coverage report
+bun run test:watch    # Run in watch mode
 ```
 
 Frontend:
 ```bash
 cd frontend
-npm test              # Run in watch mode
-npm run test:coverage # Run with coverage report
+bun test              # Run in watch mode
+bun run test:coverage # Run with coverage report
 ```
 
 ### Test Coverage