[web] Use "router link" for the list of index buttons

web-src/src/components/IndexButtonList.vue

@@ -1,13 +1,13 @@
 <template>
   <section>
     <nav class="buttons is-centered mb-4 fd-is-square">
-      <a
-        v-for="char in index"
-        :key="char"
+      <router-link
+        v-for="id in index"
+        :key="id"
         class="button is-small"
-        @click="nav(char)"
-        v-text="char"
-      />
+        :to="'#index_' + id"
+        >{{ id }}</router-link
+      >
     </nav>
   </section>
 </template>
@@ -15,12 +15,7 @@
 <script>
 export default {
   name: 'IndexButtonList',
-  props: ['index'],
-  methods: {
-    nav(id) {
-      this.$router.push({ hash: '#index_' + id })
-    }
-  }
+  props: ['index']
 }
 </script>