feat: refactor and optimize frontend with Next.js App Router, TypeScript, and Tailwind CSS

- Complete refactoring of old frontend into Next.js App Router workspace
- Redesigned sidebar collapsing animation with absolute toggle positioning
- Resolved visual canvas bleed transitions between light/dark themes
- Added custom dark theme variant for toggle switch buttons
- Implemented full localization across Indonesian, English, Spanish, Japanese, and Chinese
- Synchronized HTML document themes to apply dark mode styles to portals/overlays

frontend/_next/static/ncF6Dp_0OCMhTp1KUVnS4/_buildManifest.js

@@ -0,0 +1,11 @@
+self.__BUILD_MANIFEST = {
+  "__rewrites": {
+    "afterFiles": [],
+    "beforeFiles": [],
+    "fallback": []
+  },
+  "sortedPages": [
+    "/_app",
+    "/_error"
+  ]
+};self.__BUILD_MANIFEST_CB && self.__BUILD_MANIFEST_CB()