Add canonical per-provider model lists with picker UI

The catalog only carried one defaultModel string per provider, which
forced users to type model ids by hand and made the onboarding /
providers panel feel like the original AgentCompany was missing models.

- src/shared/provider-models.ts holds the canonical id/name list per
  provider key (~165 entries across OpenAI, Anthropic, xAI, Groq,
  GitHub Copilot, Antigravity, GPT account, Azure, Bedrock, Vertex)
- ProviderCatalogEntry now exposes a models[] array
- Onboarding ProviderStep renders a <select> populated from the active
  provider's catalog instead of a freeform text input
- ProvidersPanel connect dialog uses the same picker for API key,
  OAuth, and account auth flows
- TeamPage hire dialog adds a <datalist> with every catalog model so
  manual entry is autocompletable

AgentCompany-New/src/shared/provider-catalog.ts

@@ -1,11 +1,12 @@
 import { PROVIDER_AUTH_TYPE, type ProviderCatalogEntry } from "./domain";
+import { listProviderModels } from "./provider-models";
 
-export const PROVIDER_CATALOG: ProviderCatalogEntry[] = [
+const RAW_CATALOG: Omit<ProviderCatalogEntry, "models">[] = [
   {
     key: "openai",
     label: "OpenAI",
     authType: PROVIDER_AUTH_TYPE.API_KEY,
-    defaultModel: "gpt-5.1",
+    defaultModel: "gpt-5.4",
     capabilityTags: ["responses", "tools", "background"],
     signInUrl: null,
     credentialHelp: "Generate an API key at platform.openai.com → API keys.",
@@ -92,3 +93,8 @@ export const PROVIDER_CATALOG: ProviderCatalogEntry[] = [
     credentialHelp: "Provide GCP project id, region, and a service-account JSON key with aiplatform.user role.",
   },
 ];
+
+export const PROVIDER_CATALOG: ProviderCatalogEntry[] = RAW_CATALOG.map((entry) => ({
+  ...entry,
+  models: listProviderModels(entry.key),
+}));