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.

cmd/llm/main.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/joho/godotenv"
+)
+
+func main() {
+	// Load .env file if it exists (ignore error if not found)
+	_ = godotenv.Load()
+
+	p := tea.NewProgram(
+		InitialModel(),
+		tea.WithAltScreen(),
+		tea.WithMouseCellMotion(),
+	)
+
+	if _, err := p.Run(); err != nil {
+		fmt.Printf("Error running program: %v\n", err)
+		os.Exit(1)
+	}
+}