feat: Optimize build and dependencies

Introduce manual chunking for vendor dependencies to improve load times.
Update Node.js engine requirement to >=18.0.0.
Refactor `AccountsReceivableView` by removing commented-out code and unnecessary variables.
Add a development server port configuration.

index.html

@@ -14,9 +14,9 @@
       
       body {
         font-family: 'Akzidenz Grotesk', 'Helvetica Neue', Helvetica, Arial, sans-serif;
-        background-color: #F8FAFC; /* Slate 50 */
+        background-color: #F8FAFC;
       }
-      /* Custom scrollbar */
+
       ::-webkit-scrollbar {
         width: 8px;
         height: 8px;
@@ -66,17 +66,17 @@
   <script type="importmap">
 {
   "imports": {
-    "vite": "https://esm.sh/vite@^7.3.1",
-    "@google/genai": "https://esm.sh/@google/genai@^1.40.0",
-    "recharts": "https://esm.sh/recharts@^3.7.0",
-    "path": "https://esm.sh/path@^0.12.7",
-    "react/": "https://esm.sh/react@^19.2.4/",
     "react": "https://esm.sh/react@^19.2.4",
-    "express": "https://esm.sh/express@^5.2.1",
     "react-dom/": "https://esm.sh/react-dom@^19.2.4/",
-    "url": "https://esm.sh/url@^0.11.4",
+    "react/": "https://esm.sh/react@^19.2.4/",
+    "recharts": "https://esm.sh/recharts@^3.7.0",
+    "lucide-react": "https://esm.sh/lucide-react@^0.563.0",
+    "@google/genai": "https://esm.sh/@google/genai@^1.40.0",
+    "vite": "https://esm.sh/vite@^7.3.1",
     "@vitejs/plugin-react": "https://esm.sh/@vitejs/plugin-react@^5.1.3",
-    "lucide-react": "https://esm.sh/lucide-react@^0.563.0"
+    "express": "https://esm.sh/express@^5.2.1",
+    "path": "https://esm.sh/path@^0.12.7",
+    "url": "https://esm.sh/url@^0.11.4"
   }
 }
 </script>