Fix z.ai thinking/reasoning params, fixes #688

Z.ai uses thinking: { type: "enabled" | "disabled" } instead of
OpenAI's reasoning_effort. Added thinkingFormat compat flag to handle
this. Thinking is now explicitly enabled/disabled based on user setting.

packages/ai/scripts/generate-models.ts

@@ -440,6 +440,7 @@ async function loadModelsDevData(): Promise<Model<any>[]> {
 				},
 				compat: {
 					supportsDeveloperRole: false,
+					thinkingFormat: "zai",
 				},
 				contextWindow: m.limit?.context || 4096,
 				maxTokens: m.limit?.output || 4096,