feat: add Moonshot auth choice

src/agents/model-auth.ts

@@ -146,6 +146,7 @@ export function resolveEnvApiKey(provider: string): EnvApiKeyResult | null {
     cerebras: "CEREBRAS_API_KEY",
     xai: "XAI_API_KEY",
     openrouter: "OPENROUTER_API_KEY",
+    moonshot: "MOONSHOT_API_KEY",
     minimax: "MINIMAX_API_KEY",
     mistral: "MISTRAL_API_KEY",
     opencode: "OPENCODE_API_KEY",