refactor(ui): consolidate 7 hand-rolled kebabs into one KebabMenu (DRY pattern sweep)

First pattern-consistency DRY pass (process #594). The overflow kebab was
hand-rolled 7 ways in two divergent activator strategies — Pattern A
(#activator + v-bind) which silently breaks inside the teleported image modal
(#711), and Pattern B (manual v-model + activator=parent + open-on-click=false +
z-index 2400) the modal kebabs needed as a workaround.

New <KebabMenu> (components/common) bakes in the modal-safe strategy
UNIVERSALLY, so every kebab works in modal and non-modal contexts — folding the
latent #711-class bug fix into all five Pattern-A sites. Menu items go in the
default slot; variations (size/variant/location/label/min-width) are props.

Adopted across all 7: TagChip, SuggestionItem, TagCard, SeriesView card,
SeriesManageView, BackupRunsTable, SourceActions. Exhaustiveness (§8b):
mdi-dots-vertical now lives only in KebabMenu. Labeled dropdowns / nav menus /
filter popovers are a different concept and left alone. Seeded the pattern
catalog so new code reuses the primitive. Test: KebabMenu renders slot items +
trigger label/glyph + presentational props.

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

frontend/src/components/subscriptions/SourceActions.vue

@@ -26,40 +26,33 @@
       </v-tooltip>
     </v-btn>
 
-    <v-menu location="bottom end">
-      <template #activator="{ props: menuProps }">
-        <v-btn icon size="small" variant="text" v-bind="menuProps" @click.stop>
-          <v-icon>mdi-dots-vertical</v-icon>
-          <v-tooltip activator="parent" location="top">More actions</v-tooltip>
-        </v-btn>
-      </template>
-      <v-list density="compact" min-width="260">
-        <v-list-item
-          v-if="isPatreon && !running"
-          prepend-icon="mdi-backup-restore"
-          @click="emit('recover', source)"
-        >
-          <v-list-item-title>Recover dropped near-duplicates</v-list-item-title>
-          <v-list-item-subtitle>
-            Re-fetch images previously dropped as near-dups and re-judge them
-            under the current similarity threshold
-          </v-list-item-subtitle>
-        </v-list-item>
-        <v-divider v-if="isPatreon && !running" />
-        <v-list-item
-          base-color="error"
-          prepend-icon="mdi-delete-outline"
-          @click="emit('remove', source)"
-        >
-          <v-list-item-title>Remove source</v-list-item-title>
-        </v-list-item>
-      </v-list>
-    </v-menu>
+    <KebabMenu size="small" :min-width="260" label="More actions">
+      <v-list-item
+        v-if="isPatreon && !running"
+        prepend-icon="mdi-backup-restore"
+        @click="emit('recover', source)"
+      >
+        <v-list-item-title>Recover dropped near-duplicates</v-list-item-title>
+        <v-list-item-subtitle>
+          Re-fetch images previously dropped as near-dups and re-judge them
+          under the current similarity threshold
+        </v-list-item-subtitle>
+      </v-list-item>
+      <v-divider v-if="isPatreon && !running" />
+      <v-list-item
+        base-color="error"
+        prepend-icon="mdi-delete-outline"
+        @click="emit('remove', source)"
+      >
+        <v-list-item-title>Remove source</v-list-item-title>
+      </v-list-item>
+    </KebabMenu>
   </div>
 </template>
 
 <script setup>
 import { computed } from 'vue'
+import KebabMenu from '../common/KebabMenu.vue'
 
 const props = defineProps({
   source: { type: Object, required: true },