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.__PAGE__.txt

@@ -0,0 +1,9 @@
+1:"$Sreact.fragment"
+2:I[47257,["/_next/static/chunks/0dbhjjzl8qfwv.js"],"ClientPageRoot"]
+3:I[52683,["/_next/static/chunks/0dbhjjzl8qfwv.js","/_next/static/chunks/01yjdu1pd4sew.js"],"default"]
+6:I[97367,["/_next/static/chunks/0dbhjjzl8qfwv.js"],"OutletBoundary"]
+7:"$Sreact.suspense"
+0:{"rsc":["$","$1","c",{"children":[["$","$L2",null,{"Component":"$3","serverProvidedParams":{"searchParams":{},"params":{},"promises":["$@4","$@5"]}}],[["$","script","script-0",{"src":"/_next/static/chunks/01yjdu1pd4sew.js","async":true}]],["$","$L6",null,{"children":["$","$7",null,{"name":"Next.MetadataOutlet","children":"$@8"}]}]]}],"isPartial":false,"staleTime":300,"varyParams":null,"buildId":"ncF6Dp_0OCMhTp1KUVnS4"}
+4:{}
+5:"$0:rsc:props:children:0:props:serverProvidedParams:params"
+8:null