Use zustand for state management

frontend/package-lock.json

@@ -12,7 +12,8 @@
         "@tanstack/react-query-devtools": "^5.74.6",
         "react": "^19.0.0",
         "react-dom": "^19.0.0",
-        "react-router-dom": "^7.5.1"
+        "react-router-dom": "^7.5.1",
+        "zustand": "^5.0.3"
       },
       "devDependencies": {
         "@eslint/js": "^9.22.0",
@@ -1471,7 +1472,7 @@
       "version": "19.1.2",
       "resolved": "https://registry.npmjs.org/@types/react/-/react-19.1.2.tgz",
       "integrity": "sha512-oxLPMytKchWGbnQM9O7D67uPa9paTNxO7jVoNMXgkkErULBPhPARCfkKL9ytcIJJRGjbsVwW4ugJzyFFvm/Tiw==",
-      "dev": true,
+      "devOptional": true,
       "license": "MIT",
       "dependencies": {
         "csstype": "^3.0.2"
@@ -1963,7 +1964,7 @@
       "version": "3.1.3",
       "resolved": "https://registry.npmjs.org/csstype/-/csstype-3.1.3.tgz",
       "integrity": "sha512-M1uQkMl8rQK/szD0LNhtqxIPLpimGm8sOBwU7lLnCpSbTyY3yeU1Vc7l4KT5zT4s/yOxHH5O7tIuuLOCnLADRw==",
-      "dev": true,
+      "devOptional": true,
       "license": "MIT"
     },
     "node_modules/debug": {
@@ -3436,6 +3437,35 @@
       "funding": {
         "url": "https://github.com/sponsors/sindresorhus"
       }
+    },
+    "node_modules/zustand": {
+      "version": "5.0.3",
+      "resolved": "https://registry.npmjs.org/zustand/-/zustand-5.0.3.tgz",
+      "integrity": "sha512-14fwWQtU3pH4dE0dOpdMiWjddcH+QzKIgk1cl8epwSE7yag43k/AD/m4L6+K7DytAOr9gGBe3/EXj9g7cdostg==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=12.20.0"
+      },
+      "peerDependencies": {
+        "@types/react": ">=18.0.0",
+        "immer": ">=9.0.6",
+        "react": ">=18.0.0",
+        "use-sync-external-store": ">=1.2.0"
+      },
+      "peerDependenciesMeta": {
+        "@types/react": {
+          "optional": true
+        },
+        "immer": {
+          "optional": true
+        },
+        "react": {
+          "optional": true
+        },
+        "use-sync-external-store": {
+          "optional": true
+        }
+      }
     }
   }
 }