Implemented simple chat

.github/workflows/README.md

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+# GitHub Actions CI/CD
+
+This directory contains the continuous integration workflows for the Simple Chat application.
+
+## Workflows
+
+### `ci.yml` - Continuous Integration
+
+**Triggers:**
+- Push to `main` branch
+- Pull requests to `main` branch
+
+**Jobs:**
+
+#### 1. Code Formatting Check (`format`)
+- **Platform:** Ubuntu Latest
+- **Timeout:** 10 minutes
+- **Purpose:** Ensures code follows Rust formatting standards
+- **Command:** `cargo fmt --all -- --check`
+
+#### 2. Linting (`lint`)
+- **Platform:** Ubuntu Latest
+- **Timeout:** 15 minutes
+- **Purpose:** Static analysis and linting with Clippy
+- **Command:** `cargo clippy --all-targets --all-features -- -D warnings`
+- **Features:** Treats warnings as errors for high code quality
+
+#### 3. Unit and Integration Tests (`test`)
+- **Platforms:** Ubuntu, Windows, macOS
+- **Timeout:** 30 minutes
+- **Purpose:** Comprehensive testing across platforms
+- **Tests:**
+  - Unit tests (`cargo test --lib`)
+  - Integration tests (`cargo test --tests`)
+  - Binary compilation verification
+
+#### 4. End-to-End Integration Test (`e2e`)
+- **Platform:** Ubuntu Latest
+- **Timeout:** 20 minutes
+- **Purpose:** Full system integration testing
+- **Tests:**
+  1. **Basic Client-Server Communication**
+     - Starts server in background
+     - Connects client and sends test message
+     - Verifies successful communication
+
+  2. **Multiple Clients Test**
+     - Spawns multiple concurrent clients
+     - Tests message exchange between users
+     - Validates server handles concurrent connections
+
+  3. **Server Responsiveness**
+     - Checks server remains responsive after load
+     - Validates connection acceptance after multiple clients
+     - Ensures proper resource management
+
+#### 5. Build Verification (`build-check`)
+- **Platforms:** Ubuntu, Windows, macOS
+- **Timeout:** 15 minutes  
+- **Purpose:** Cross-platform build verification
+- **Tests:**
+  - Debug build compilation
+  - Release build compilation
+  - Binary help command functionality
+
+#### 6. CI Success Summary (`ci-success`)
+- **Platform:** Ubuntu Latest
+- **Purpose:** Aggregates results from all jobs
+- **Behavior:** Fails if any dependent job fails
+
+## Features
+
+### Robust Error Handling
+- **Timeouts:** All jobs have appropriate timeout limits
+- **Cleanup:** Proper server process cleanup in E2E tests
+- **Trap handling:** Signal handling for graceful shutdowns
+- **Exit codes:** Proper error reporting and propagation
+
+### Performance Optimization
+- **Caching:** Rust dependencies cached using `Swatinem/rust-cache`
+- **Parallel execution:** Jobs run concurrently where possible
+- **Incremental builds:** Cache keys based on `Cargo.lock` checksums
+
+### Cross-Platform Support
+- **Linux (Ubuntu):** Primary development and testing platform
+- **Windows:** Compatibility verification  
+- **macOS:** Apple silicon and x86_64 support
+- **Binary verification:** Platform-specific binary testing
+
+### Comprehensive Testing Strategy
+- **Unit Tests:** Core functionality and message protocol
+- **Integration Tests:** Server-client interaction
+- **End-to-End Tests:** Real-world usage scenarios
+- **Build Tests:** Compilation verification across platforms
+
+## Usage
+
+### Local Development
+```bash
+# Run the same checks locally before pushing
+cargo fmt --all -- --check
+cargo clippy --all-targets --all-features -- -D warnings
+cargo test
+cargo build --release
+```
+
+### Monitoring CI
+- **Status:** Check the Actions tab in GitHub repository
+- **Logs:** View detailed logs for each job step
+- **Artifacts:** Download build artifacts if configured
+- **Notifications:** Configure GitHub notifications for failures
+
+### Troubleshooting
+
+**Common Issues:**
+- **Format failures:** Run `cargo fmt` to fix formatting
+- **Clippy warnings:** Fix warnings or add `#[allow(...)]` where appropriate
+- **Test timeouts:** Check for infinite loops or blocking operations
+- **E2E failures:** Verify server starts correctly and ports are available
+
+**Debug Steps:**
+1. Check job logs for specific error messages
+2. Reproduce issues locally using the same commands
+3. Verify environment variables and dependencies
+4. Test on the same platform as failing CI job
+
+## Configuration
+
+### Environment Variables
+- `CARGO_TERM_COLOR=always` - Colored output in CI logs
+- `RUST_BACKTRACE=1` - Full backtraces on panics
+- `RUST_LOG=info` - Logging level for integration tests
+
+### Timeouts
+- **Format:** 10 minutes (formatting is fast)
+- **Lint:** 15 minutes (clippy analysis takes time)
+- **Tests:** 30 minutes (includes multiple platforms)
+- **E2E:** 20 minutes (includes server startup and multiple test scenarios)
+- **Build:** 15 minutes (cross-platform builds)
+
+### Dependencies
+- **Rust toolchain:** Managed by `dtolnay/rust-toolchain`
+- **Caching:** Handled by `Swatinem/rust-cache`
+- **Checkout:** Uses `actions/checkout@v4`