feat(config): add complete model_list template with all 17 providers

- Include all 17 supported providers in default config as templates
- Each entry has model_name, model, api_base, and empty api_key
- Add comments with API key links for each provider
- Keep onboard message simple (only OpenRouter and Ollama)
- Fix duplicate model_name (cerebras-llama-3.3-70b)

Providers included:
Zhipu, OpenAI, Anthropic, DeepSeek, Gemini, Qwen, Moonshot,
Groq, OpenRouter, NVIDIA, Cerebras, Volcengine, ShengsuanYun,
Antigravity, GitHub Copilot, Ollama, VLLM

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cmd/picoclaw/cmd_onboard.go

@@ -43,7 +43,13 @@ func onboard() {
 	fmt.Printf("%s picoclaw is ready!\n", logo)
 	fmt.Println("\nNext steps:")
 	fmt.Println("  1. Add your API key to", configPath)
-	fmt.Println("     Get one at: https://openrouter.ai/keys")
+	fmt.Println("")
+	fmt.Println("     Recommended:")
+	fmt.Println("     - OpenRouter: https://openrouter.ai/keys (access 100+ models)")
+	fmt.Println("     - Ollama:     https://ollama.com (local, free)")
+	fmt.Println("")
+	fmt.Println("     See README.md for 17+ supported providers.")
+	fmt.Println("")
 	fmt.Println("  2. Chat: picoclaw agent -m \"Hello!\"")
 }