fix(series): sticky tabs + controls on the Series view

The Series tab strip and the Browse search/sort (and Suggestions controls)
scrolled away on a long grid (operator-asked). Hoist the tabs + active-tab
controls into one sticky header pinned under the 64px TopNav. The controls
had to leave v-window — it clips sticky children — so they're driven by the
tab from the header instead of living inside each window-item.

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

frontend/src/views/SeriesView.vue

@@ -1,35 +1,60 @@
 <template>
   <v-container fluid class="pt-2 pb-6">
-    <v-tabs v-model="tab" density="compact" class="mb-3">
-      <v-tab value="browse">Browse</v-tab>
-      <v-tab value="suggestions">
-        Suggestions
-        <v-badge
-          v-if="sug.suggestions.length" :content="sug.suggestions.length"
-          inline color="accent"
+    <!-- Tabs + the active tab's controls live in one sticky block pinned under
+         the 64px TopNav (operator-asked 2026-06-12), so the axis switcher and
+         search/sort stay reachable on a long grid. The controls can't sit
+         inside v-window (it clips sticky children), so they're hoisted here. -->
+    <div class="fc-series__head">
+      <v-tabs v-model="tab" density="compact">
+        <v-tab value="browse">Browse</v-tab>
+        <v-tab value="suggestions">
+          Suggestions
+          <v-badge
+            v-if="sug.suggestions.length" :content="sug.suggestions.length"
+            inline color="accent"
+          />
+        </v-tab>
+      </v-tabs>
+
+      <div v-if="tab === 'browse'" class="fc-series-browse__controls">
+        <v-text-field
+          v-model="query"
+          density="compact" variant="outlined" hide-details clearable
+          label="Search series" prepend-inner-icon="mdi-magnify"
+          style="max-width: 320px;"
         />
-      </v-tab>
-    </v-tabs>
+        <v-select
+          :model-value="store.sort"
+          :items="sortItems"
+          density="compact" variant="outlined" hide-details
+          label="Sort" style="max-width: 220px;"
+          @update:model-value="store.setSort($event)"
+        />
+      </div>
+
+      <div v-else class="fc-sug__controls">
+        <v-switch
+          :model-value="sug.enabled" color="accent" density="compact"
+          hide-details label="Matching on"
+          @update:model-value="sug.setEnabled($event)"
+        />
+        <v-text-field
+          :model-value="sug.threshold"
+          type="number" min="0" max="1" step="0.05"
+          density="compact" variant="outlined" hide-details
+          label="Threshold" style="max-width: 130px;"
+          @change="sug.setThreshold(Number($event.target.value))"
+        />
+        <v-spacer />
+        <v-btn
+          variant="tonal" prepend-icon="mdi-radar" @click="sug.rescan()"
+        >Rescan</v-btn>
+      </div>
+    </div>
 
     <v-window v-model="tab">
       <!-- ---- Browse ---- -->
       <v-window-item value="browse">
-        <div class="fc-series-browse__controls">
-          <v-text-field
-            v-model="query"
-            density="compact" variant="outlined" hide-details clearable
-            label="Search series" prepend-inner-icon="mdi-magnify"
-            style="max-width: 320px;"
-          />
-          <v-select
-            :model-value="store.sort"
-            :items="sortItems"
-            density="compact" variant="outlined" hide-details
-            label="Sort" style="max-width: 220px;"
-            @update:model-value="store.setSort($event)"
-          />
-        </div>
-
         <v-alert v-if="store.error" type="error" variant="tonal" closable class="my-4">
           Failed to load: {{ store.error }}
         </v-alert>
@@ -138,25 +163,6 @@
 
       <!-- ---- Suggestions ---- -->
       <v-window-item value="suggestions">
-        <div class="fc-sug__controls">
-          <v-switch
-            :model-value="sug.enabled" color="accent" density="compact"
-            hide-details label="Matching on"
-            @update:model-value="sug.setEnabled($event)"
-          />
-          <v-text-field
-            :model-value="sug.threshold"
-            type="number" min="0" max="1" step="0.05"
-            density="compact" variant="outlined" hide-details
-            label="Threshold" style="max-width: 130px;"
-            @change="sug.setThreshold(Number($event.target.value))"
-          />
-          <v-spacer />
-          <v-btn
-            variant="tonal" prepend-icon="mdi-radar" @click="sug.rescan()"
-          >Rescan</v-btn>
-        </div>
-
         <v-alert v-if="sug.error" type="error" variant="tonal" closable class="my-4">
           {{ sug.error }}
         </v-alert>
@@ -287,8 +293,17 @@ onMounted(() => {
 </script>
 
 <style scoped>
+/* Sticky header (tabs + active-tab controls) pinned under the 64px TopNav, so
+   content scrolls cleanly beneath it. Surface bg matches SettingsView. */
+.fc-series__head {
+  position: sticky;
+  top: 64px;
+  z-index: 4;
+  background: rgb(var(--v-theme-surface));
+  padding-bottom: 12px;
+}
 .fc-series-browse__controls {
-  display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 16px;
+  display: flex; flex-wrap: wrap; gap: 12px; padding-top: 12px;
 }
 .fc-series-browse__empty {
   padding: 48px; text-align: center;
@@ -351,7 +366,7 @@ onMounted(() => {
 
 /* Suggestions tab */
 .fc-sug__controls {
-  display: flex; align-items: center; gap: 16px; margin-bottom: 12px;
+  display: flex; align-items: center; gap: 16px; padding-top: 12px;
 }
 .fc-sug__list { display: flex; flex-direction: column; gap: 8px; }
 .fc-sug__row {