TS7 upgrade + write to TS over JS

frontend/package.json

@@ -7,6 +7,7 @@
         "dev": "vite",
         "build": "vite build",
         "lint": "eslint .",
+        "typecheck": "node_modules/typescript-7/bin/tsc --noEmit",
         "preview": "vite preview"
     },
     "dependencies": {
@@ -34,6 +35,9 @@
         "eslint-plugin-react-refresh": "^0.5.2",
         "globals": "^17.4.0",
         "prettier": "^3.8.3",
+        "typescript": "^6.0.3",
+        "typescript-7": "npm:typescript@^7.0.1-rc",
+        "typescript-eslint": "^8.61.1",
         "typescript-language-server": "^5.3.0",
         "vite": "^8.0.4",
         "vscode-langservers-extracted": "^4.10.0"