feat(admin): configure model providers from database

frontend/src/app/api/birth-time-guide/route.ts

@@ -18,7 +18,7 @@ import { createAdminSupabaseClient } from "@/lib/supabase/admin";
 import { isSupabaseConfigurationError } from "@/lib/supabase/config";
 import { createServerSupabaseClient } from "@/lib/supabase/server";
 import { getBirthTimeGuideAgent } from "@/mastra";
-import { defaultLanguageModel } from "@/mastra/model";
+import { loadLanguageModelCatalog } from "@/lib/model-catalog";
 import {
   recordJourneyTransitionMetric,
 } from "@/lib/birth-time-journey-telemetry";
@@ -71,7 +71,8 @@ export async function POST(request: Request) {
     store,
     engine: createJyotishBirthTimeJourneyEngine(),
   });
-  const model = defaultLanguageModel();
+  const catalog = await loadLanguageModelCatalog();
+  const model = catalog.models.find((entry) => entry.id === catalog.defaultModelId) ?? null;
   const generator = model
     ? {
         async generate(prompt: string) {