feat(frontend): enable TypeScript strict mode for better type safety

Enable strict TypeScript compilation options in the Vue 3 frontend
to catch more potential bugs at compile time and improve code quality.

webapp/tsconfig.json

@@ -5,6 +5,9 @@
     { "path": "./tsconfig.node.json" }
   ],
   "compilerOptions": {
+    "strict": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
     "baseUrl": ".",
     "paths": {
       "@/*": ["./src/*"]