feat: simplify LLM config and onboarding

apps/x/packages/shared/src/models.ts

@@ -0,0 +1,13 @@
+import { z } from "zod";
+
+export const LlmProvider = z.object({
+  flavor: z.enum(["openai", "anthropic", "google", "openrouter", "aigateway", "ollama", "openai-compatible"]),
+  apiKey: z.string().optional(),
+  baseURL: z.string().optional(),
+  headers: z.record(z.string(), z.string()).optional(),
+});
+
+export const LlmModelConfig = z.object({
+  provider: LlmProvider,
+  model: z.string(),
+});