Add Nix and environment configuration files

- Created `.envrc` for Direnv integration to manage Nix environment.
- Added `.gitignore` to exclude build artifacts and IDE files.
- Introduced `flake.nix` for Nix flake configuration and development shell setup.
- Generated `flake.lock` to lock dependencies for the Nix environment.
- Updated `go.mod` to specify Go version 1.23.
- Added `README.md` with project overview, development instructions, and troubleshooting tips.

README.md

@@ -0,0 +1,102 @@
+# ARR Go Client
+
+A Go client for ARR applications (Radarr, Sonarr, etc.).
+
+## Development with Nix
+
+This project uses Nix for dependency management and development environment setup.
+
+### Prerequisites
+
+- [Nix](https://nixos.org/download.html) installed on your system
+- [direnv](https://direnv.net/) (optional, for automatic environment activation)
+
+### Quick Start
+
+1. **Enter the development shell:**
+   ```bash
+   nix develop
+   ```
+
+2. **Run the application:**
+   ```bash
+   go run .
+   ```
+
+### Development Commands
+
+Once in the Nix shell, you can use standard Go commands:
+
+```bash
+# Run the application
+go run .
+
+# Run tests
+go test ./...
+
+# Clean up dependencies
+go mod tidy
+
+# Download dependencies
+go mod download
+
+# Build the binary
+go build -o arr-go-client .
+```
+
+### Available Tools
+
+The Nix development environment includes:
+
+- **Go 1.23** - Latest stable Go version available in Nix
+
+### Project Structure
+
+```
+arr-go-client/
+├── flake.nix          # Nix flake configuration
+├── .envrc             # Direnv configuration (auto-loads Nix environment)
+├── go.mod             # Go module file
+├── main.go            # Main application
+├── client.go          # Client implementation
+├── interfaces.go      # Interface definitions
+├── types.go           # Type definitions
+└── radarr.go          # Radarr-specific code
+```
+
+### Troubleshooting
+
+#### Flake Lock Issues
+
+If you need to update the flake lock:
+
+```bash
+nix flake update
+```
+
+#### Experimental Features Disabled
+
+If you get errors about experimental features being disabled, you can enable them globally:
+
+1. **Edit your global Nix config:**
+   ```bash
+   mkdir -p ~/.config/nix
+   echo "experimental-features = nix-command flakes" >> ~/.config/nix/nix.conf
+   ```
+
+2. **Or run with explicit experimental features:**
+   ```bash
+   nix --extra-experimental-features 'nix-command flakes' develop
+   ```
+
+### Contributing
+
+1. Fork the repository
+2. Create a feature branch
+3. Make your changes
+4. Test with `nix develop` and `go test ./...`
+5. Submit a pull request
+
+### License
+
+[Add your license here]