feat: cache-control header

Author: martinwang2002

staticwebapp.config.json

@@ -4,5 +4,13 @@
     "exclude": [
       "*.{jpg,gif,png,ico,svg,css,scss,js}"
     ]
-  }
+  },
+  "routes": [
+    {
+      "route": "/*.{jpg,gif,png,ico,svg,css,scss,js,webp,webmanifest}",
+      "headers": {
+        "cache-control": "public, max-age=31536000, immutable"
+      }
+    }
+  ]
 }