feat(artist): editable display name + rename surface; drop name-uniqueness (#130 step 1)

First step of decoupling artist identity/storage/display. migration 0077 drops
uq_artist_name so the display name is free text (two genuinely different creators
can share a name); the slug stays the immutable, unique storage/identity key (the
on-disk path component — untouched, so nothing moves). ArtistService.rename +
PATCH /api/artists/<id> change the name ONLY. Frontend: inline pencil-edit on the
artist header (mirrors TagCard), slug/route unaffected so no navigation. Fixes the
operator's 'no surface to rename an artist' + the name-collision fragility.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CDgx8bQS5YrGRK76v8HUnM

frontend/src/components/artist/ArtistHeader.vue

@@ -1,8 +1,21 @@
 <template>
   <header class="fc-artist-header">
     <div class="fc-artist-header__left">
-      <h1 class="fc-artist-header__name">{{ name }}</h1>
-      <span v-if="stats" class="fc-artist-header__stats">{{ stats }}</span>
+      <template v-if="!editing">
+        <h1 class="fc-artist-header__name">{{ name }}</h1>
+        <v-icon
+          class="fc-artist-header__edit" size="16" icon="mdi-pencil"
+          title="Rename artist (display name only)" @click="startEdit"
+        />
+      </template>
+      <v-text-field
+        v-else
+        v-model="draft"
+        density="compact" variant="outlined" hide-details autofocus
+        class="fc-artist-header__edit-field"
+        @keydown.enter="submit" @keydown.esc="cancel" @blur="cancel"
+      />
+      <span v-if="stats && !editing" class="fc-artist-header__stats">{{ stats }}</span>
     </div>
     <v-tabs
       :model-value="modelValue"
@@ -34,7 +47,7 @@
 </template>
 
 <script setup>
-import { computed } from 'vue'
+import { computed, ref } from 'vue'
 import { formatLocalDate } from '../../utils/date.js'
 
 const props = defineProps({
@@ -45,7 +58,23 @@ const props = defineProps({
   modelValue:  { type: String, required: true },
 })
 
-defineEmits(['update:modelValue'])
+const emit = defineEmits(['update:modelValue', 'rename'])
+
+// Inline rename (display name only — #130). Mirrors TagCard's pencil-edit.
+const editing = ref(false)
+const draft = ref('')
+function startEdit () {
+  draft.value = props.name
+  editing.value = true
+}
+function cancel () {
+  editing.value = false
+}
+function submit () {
+  const next = draft.value.trim()
+  editing.value = false
+  if (next && next !== props.name) emit('rename', next)
+}
 
 const stats = computed(() => {
   const parts = []
@@ -111,6 +140,20 @@ const stats = computed(() => {
   text-overflow: ellipsis;
 }
 
+.fc-artist-header__edit {
+  flex: 0 0 auto;
+  opacity: 0;
+  cursor: pointer;
+  color: rgb(var(--v-theme-on-surface-variant));
+  transition: opacity .15s ease;
+}
+.fc-artist-header__left:hover .fc-artist-header__edit { opacity: .7; }
+.fc-artist-header__edit:hover { opacity: 1; }
+.fc-artist-header__edit-field {
+  max-width: 340px;
+  font-family: 'Fraunces', Georgia, serif;
+}
+
 .fc-artist-header__tabs {
   flex: 0 0 auto;
 }

frontend/src/stores/artist.js

@@ -73,6 +73,16 @@ export const useArtistStore = defineStore('artist', () => {
     }
   }
 
+  // Rename the DISPLAY name only (#130). The slug is immutable, so the route
+  // (slug-based) and on-disk paths are unaffected — just patch the shown name.
+  async function rename (name) {
+    if (!overview.value) return
+    const id = overview.value.id
+    const body = await api.patch(`/api/artists/${id}`, { body: { name } })
+    if (overview.value && overview.value.id === id) overview.value.name = body.name
+    return body
+  }
+
   const hasMoreImages = computed(() => !started || nextCursor.value !== null)
   const postCount = computed(() => overview.value?.post_count ?? null)
   const imageCount = computed(() => overview.value?.image_count ?? null)
@@ -81,6 +91,6 @@ export const useArtistStore = defineStore('artist', () => {
   return {
     overview, images, loading, imagesLoading, error, notFound,
     hasMoreImages, postCount, imageCount, lastAdded,
-    load, loadMoreImages,
+    load, loadMoreImages, rename,
   }
 })

frontend/src/views/ArtistView.vue

@@ -18,6 +18,7 @@
       :image-count="store.imageCount"
       :post-count="store.postCount"
       :last-added="store.lastAdded"
+      @rename="onRename"
     />
     <v-container fluid class="pt-2 pb-4">
       <!-- "N new since last visit" banner. Visible only on the initial
@@ -59,6 +60,7 @@ import { computed, ref, watch } from 'vue'
 import { useRoute } from 'vue-router'
 
 import { useArtistStore } from '../stores/artist.js'
+import { toast } from '../utils/toast.js'
 import ArtistHeader from '../components/artist/ArtistHeader.vue'
 import ArtistPostsTab from '../components/artist/ArtistPostsTab.vue'
 import ArtistGalleryTab from '../components/artist/ArtistGalleryTab.vue'
@@ -76,6 +78,17 @@ const { tab, resolve } = useTabQuery(
   () => ((store.postCount ?? 0) > 0 ? 'posts' : 'gallery'),
 )
 
+// Rename the artist's display name (#130). Slug/route unchanged, so no
+// navigation — the header just reflects the new name; also refresh the tab title.
+async function onRename (name) {
+  try {
+    await store.rename(name)
+    document.title = `${store.overview.name} — FabledCurator`
+  } catch (e) {
+    toast({ text: `Rename failed: ${e.message}`, type: 'error' })
+  }
+}
+
 // One-shot banner — reset on each new artist-slug load so it re-appears
 // when navigating between artists that each have unseen content.
 const unseenBanner = ref(false)