feat: Spotify integration (OAuth + voice tools)

app/api/spotify/auth/route.ts

@@ -0,0 +1,20 @@
+export const dynamic = 'force-dynamic'
+import { NextResponse } from 'next/server'
+
+export async function GET() {
+  const clientId = process.env.SPOTIFY_CLIENT_ID!
+  const redirectUri = `${process.env.NEXT_PUBLIC_APP_URL}/api/spotify/callback`
+  const scopes = [
+    'user-read-playback-state',
+    'user-modify-playback-state',
+    'user-read-currently-playing',
+  ].join(' ')
+
+  const url = new URL('https://accounts.spotify.com/authorize')
+  url.searchParams.set('response_type', 'code')
+  url.searchParams.set('client_id', clientId)
+  url.searchParams.set('scope', scopes)
+  url.searchParams.set('redirect_uri', redirectUri)
+
+  return NextResponse.redirect(url.toString())
+}