fix: move onParse to root and support trailing slash in webhook route

apps/backend/src/index.ts

@@ -29,6 +29,11 @@ const CORS_ORIGIN = process.env.CORS_ORIGIN || "http://localhost:5173";
 const JWT_SECRET = process.env.JWT_SECRET || "homaroma_secret_2026_scent";
 
 const app = new Elysia()
+  .onParse(async ({ request }) => {
+    if (request.url.includes('/api/line/webhook')) {
+      return await request.text();
+    }
+  })
   .use(
     cors({
       origin: [