build: 构建后端和Flutter Web

- 后端: mvn clean package (monisuo-1.0.jar, 41MB)
- Flutter: flutter build web --release (MaterialIcons 裁剪99.4%)
- 构建时间: 后端2s, Flutter24s

flutter_monisuo/build/web/manifest.json

@@ -0,0 +1,35 @@
+{
+    "name": "flutter_monisuo",
+    "short_name": "flutter_monisuo",
+    "start_url": ".",
+    "display": "standalone",
+    "background_color": "#0175C2",
+    "theme_color": "#0175C2",
+    "description": "A new Flutter project.",
+    "orientation": "portrait-primary",
+    "prefer_related_applications": false,
+    "icons": [
+        {
+            "src": "icons/Icon-192.png",
+            "sizes": "192x192",
+            "type": "image/png"
+        },
+        {
+            "src": "icons/Icon-512.png",
+            "sizes": "512x512",
+            "type": "image/png"
+        },
+        {
+            "src": "icons/Icon-maskable-192.png",
+            "sizes": "192x192",
+            "type": "image/png",
+            "purpose": "maskable"
+        },
+        {
+            "src": "icons/Icon-maskable-512.png",
+            "sizes": "512x512",
+            "type": "image/png",
+            "purpose": "maskable"
+        }
+    ]
+}