chore: optimize Vercel costs by removing analytics and configuring functions (#238)

- Create vercel.json with optimized function settings:
  - Chat API: 512MB memory, 120s timeout
  - Other APIs: 256MB memory, 10s timeout
- Remove @vercel/analytics package and imports
- Reduce chat route maxDuration from 300s to 120s

Expected savings: $2-4/month, keeping costs under $20 included credit

app/api/chat/route.ts

@@ -18,7 +18,7 @@ import {
 } from "@/lib/langfuse"
 import { getSystemPrompt } from "@/lib/system-prompts"
 
-export const maxDuration = 300
+export const maxDuration = 120
 
 // File upload limits (must match client-side)
 const MAX_FILE_SIZE = 2 * 1024 * 1024 // 2MB

app/layout.tsx

@@ -1,5 +1,4 @@
 import { GoogleAnalytics } from "@next/third-parties/google"
-import { Analytics } from "@vercel/analytics/react"
 import type { Metadata, Viewport } from "next"
 import { JetBrains_Mono, Plus_Jakarta_Sans } from "next/font/google"
 import { DiagramProvider } from "@/contexts/diagram-context"
@@ -117,7 +116,6 @@ export default function RootLayout({
                 className={`${plusJakarta.variable} ${jetbrainsMono.variable} antialiased`}
             >
                 <DiagramProvider>{children}</DiagramProvider>
-                <Analytics />
             </body>
             {process.env.NEXT_PUBLIC_GA_ID && (
                 <GoogleAnalytics gaId={process.env.NEXT_PUBLIC_GA_ID} />