refactor: extract back button into shared component using history navigation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/views/PublicNoteListView.vue

@@ -1,4 +1,5 @@
 <script setup lang="ts">
+import BackButton from "@/components/BackButton.vue"
 import { Author, getAka } from "@/modules/atproto/getAka"
 import { PublicNoteListItem } from "@/modules/note/models/Note"
 import { computedAsync, useAsyncState } from "@vueuse/core"
@@ -57,28 +58,7 @@ const getAlias = (did: string) =>
         </li>
       </ul>
     </div>
-    <router-link
-      :to="{ name: 'Home' }"
-      class="button is-small is-white back-button"
-    >
-      <svg
-        xmlns="http://www.w3.org/2000/svg"
-        class="icon icon-tabler icon-tabler-arrow-narrow-left"
-        width="28"
-        height="28"
-        viewBox="0 0 24 24"
-        stroke-width="1.5"
-        stroke="currentColor"
-        fill="none"
-        stroke-linecap="round"
-        stroke-linejoin="round"
-      >
-        <line x1="5" y1="12" x2="19" y2="12" />
-        <line x1="5" y1="12" x2="9" y2="16" />
-        <line x1="5" y1="12" x2="9" y2="8" />
-      </svg>
-      return home
-    </router-link>
+    <BackButton />
   </main>
 </template>