feat: complete tRPC integration and fix platform UI issues

- Implement comprehensive tRPC setup with type-safe API
- Create tRPC routers for dashboard, admin, and auth endpoints
- Migrate frontend components to use tRPC client
- Fix platform dashboard Settings button functionality
- Add platform settings page with profile and security management
- Create OpenAI API mocking infrastructure for cost-safe testing
- Update tests to work with new tRPC architecture
- Sync database schema to fix AIBatchRequest table errors

app/api/trpc/[trpc]/route.ts

@@ -0,0 +1,29 @@
+/**
+ * tRPC API Route Handler
+ *
+ * This file creates the Next.js API route that handles all tRPC requests.
+ * All tRPC procedures will be accessible via /api/trpc/*
+ */
+
+import { fetchRequestHandler } from "@trpc/server/adapters/fetch";
+import type { NextRequest } from "next/server";
+import { createTRPCContext } from "@/lib/trpc";
+import { appRouter } from "@/server/routers/_app";
+
+const handler = (req: NextRequest) =>
+  fetchRequestHandler({
+    endpoint: "/api/trpc",
+    req,
+    router: appRouter,
+    createContext: createTRPCContext,
+    onError:
+      process.env.NODE_ENV === "development"
+        ? ({ path, error }) => {
+            console.error(
+              `❌ tRPC failed on ${path ?? "<no-path>"}: ${error.message}`
+            );
+          }
+        : undefined,
+  });
+
+export { handler as GET, handler as POST };