Implement interactive CLI for LLM providers with chat, tools, and image support

- Add Bubble Tea-based CLI interface for LLM interactions.
- Implement `.env.example` for environment variable setup.
- Add provider, model, and tool selection screens.
- Include support for API key configuration.
- Enable chat interactions with optional image and tool support.
- Introduce core utility functions: image handling, tool execution, chat request management, and response rendering.
- Implement style customization with Lip Gloss.

CLAUDE.md

@@ -23,3 +23,25 @@
 - **Imports**: Organize imports into groups: standard library, then third-party libraries.
 - **Documentation**: Use standard Go doc comments for exported symbols.
 - **README.md**: The README.md file should always be kept up to date with any significant changes to the project.
+
+## CLI Tool
+- Build CLI: `go build ./cmd/llm`
+- Run CLI: `./llm` (or `llm.exe` on Windows)
+- Run without building: `go run ./cmd/llm`
+
+### CLI Features
+- Interactive TUI for testing all go-llm features
+- Support for OpenAI, Anthropic, and Google providers
+- Image input (file path, URL, or base64)
+- Tool/function calling with demo tools
+- Temperature control and settings
+
+### Key Bindings
+- `Enter` - Send message
+- `Ctrl+I` - Add image
+- `Ctrl+T` - Toggle tools panel
+- `Ctrl+P` - Change provider
+- `Ctrl+M` - Change model
+- `Ctrl+S` - Settings
+- `Ctrl+N` - New conversation
+- `Esc` - Exit/Cancel