feat(series): rename a series from the management view

The management view showed the series name but had no way to change it post-
creation (rename was only on the browse-card kebab). Add a pencil next to the
title that opens TagRenameDialog (reuses the canonical rename → PATCH
/api/tags/<id> with its collision→merge flow, since a series IS a
Tag(kind=series)); the new name reflects in place. Operator-asked 2026-06-09.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/views/SeriesManageView.vue

@@ -2,6 +2,12 @@
   <v-container fluid class="pt-2 pb-10 fc-series">
     <div class="fc-series__head">
       <span class="fc-series__name">{{ store.series?.name || 'Series' }}</span>
+      <v-btn
+        v-if="store.series"
+        icon="mdi-pencil" size="x-small" variant="text"
+        :aria-label="`Rename ${store.series.name}`"
+        @click="renameOpen = true"
+      />
       <span class="fc-series__count">
         {{ store.chapters.length }} part(s) · {{ store.pageCount }} page(s)
       </span>
@@ -214,6 +220,14 @@
         <div ref="sentinel" class="fc-picker__sentinel" />
       </div>
     </v-navigation-drawer>
+
+    <v-dialog v-model="renameOpen" max-width="420">
+      <TagRenameDialog
+        v-if="store.series"
+        :tag="{ id: store.tagId, name: store.series.name, kind: 'series' }"
+        @renamed="onRenamed" @cancel="renameOpen = false"
+      />
+    </v-dialog>
   </v-container>
 </template>
 
@@ -223,6 +237,7 @@ import { useRoute } from 'vue-router'
 import { useSeriesManageStore, moveItem } from '../stores/seriesManage.js'
 import { useInfiniteScroll } from '../composables/useInfiniteScroll.js'
 import KebabMenu from '../components/common/KebabMenu.vue'
+import TagRenameDialog from '../components/modal/TagRenameDialog.vue'
 
 const route = useRoute()
 const store = useSeriesManageStore()
@@ -231,6 +246,14 @@ const drag = ref(null)            // { chapterId, idx }
 const titleDraft = reactive({})   // chapterId -> draft title
 const partDraft = reactive({})    // chapterId -> draft stated_part (string)
 const pickerOpen = ref(false)
+const renameOpen = ref(false)
+
+// A series IS a Tag(kind=series); TagRenameDialog PATCHes /api/tags/<id> and
+// handles the same-name collision→merge flow. Reflect the new name in place.
+function onRenamed(updated) {
+  renameOpen.value = false
+  if (store.series && updated?.name) store.series.name = updated.name
+}
 
 // Keep local drafts in sync with loaded chapters. Edits commit on blur/Enter,
 // which refreshes and resets the draft to the saved value.