fix(artist-header): close gap below TopNav (top:64px → 48px to match TopNav's actual ~48px height) + center the tab strip via 1fr|auto|1fr layout with a right-side spacer cell

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/components/artist/ArtistHeader.vue

@@ -25,6 +25,11 @@
       </v-tab>
       <v-tab value="management">Management</v-tab>
     </v-tabs>
+
+    <!-- Right-side spacer: balances the left cell's flex weight so the
+         centered tabs stay geometrically centered regardless of the
+         artist-name length. Mirrors TopNav's 1fr | auto | 1fr layout. -->
+    <div class="fc-artist-header__right" />
   </header>
 </template>
 
@@ -54,11 +59,13 @@ const stats = computed(() => {
 </script>
 
 <style scoped>
-/* Matches TopNav.vue's frosted recipe exactly — top:64px parks it under
-   the 64px-tall TopNav with no visible seam. */
+/* Matches TopNav.vue's frosted recipe exactly. top:48px parks it flush
+   against TopNav's bottom edge (TopNav is 0.75rem padding + ~24px content
+   = ~48px tall; operator-flagged 2026-05-26 that top:64px left a visible
+   gap). The two bars now read as one continuous frosted strip. */
 .fc-artist-header {
   position: sticky;
-  top: 64px;
+  top: 48px;
   z-index: 4;
   display: flex;
   align-items: center;
@@ -107,6 +114,11 @@ const stats = computed(() => {
   flex: 0 0 auto;
 }
 
+.fc-artist-header__right {
+  flex: 1 1 0;
+  min-width: 0;
+}
+
 .fc-artist-header__tab-count {
   margin-left: 4px;
   font-size: 12px;