fix(aliases): store modal alias under raw model key + make aliases visible/manageable

The headline bug: aliases created from the modal NEVER resolved. Create
sent the normalized display name ('Sword', 'Uchiha Sasuke') while
resolution keys on the raw booru model key ('sword', 'uchiha_sasuke',
case-sensitive) — so the mapping was stored under a key nothing looks up,
and the prediction kept reappearing unaliased. The raw key wasn't even in
the /suggestions response, so the modal couldn't send it.

- Suggestion now carries raw_name (the model key an alias must use) and
  via_alias (surfaced via an operator alias); both serialized by the API.
- Modal alias-create sends raw_name, not display_name (the fix). Aliased
  suggestions show an 'alias' badge and a 'Remove alias' action; 'Treat as
  alias for…' is hidden for centroid hits (no model key) and already-aliased
  rows.
- Tag-side management: TagCard ⋮ → 'Aliases…' opens a dialog listing the
  model keys that fold into a tag, with remove (GET /api/tags/<id>/aliases +
  AliasService.list_for_tag). Creation stays in the modal suggestion flow.

Tests: full API round-trip locking the raw-key contract (raw_name exposed →
alias authored with it → resolves + via_alias on a later image);
list_for_tag (service + API); via_alias/raw_name on the existing service
suggestion tests. No migration.

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

frontend/src/components/modal/SuggestionsPanel.vue

@@ -17,13 +17,15 @@
         v-for="cat in peopleCats" :key="cat"
         v-show="store.byCategory[cat] && store.byCategory[cat].length"
         :label="labelFor(cat)" :items="store.byCategory[cat] || []"
-        @accept="onAccept" @alias="onAlias" @dismiss="store.dismiss"
+        @accept="onAccept" @alias="onAlias" @remove-alias="onRemoveAlias"
+        @dismiss="store.dismiss"
       />
       <SuggestionsCategoryGroup
         v-if="store.byCategory.general && store.byCategory.general.length"
         label="General" :items="store.byCategory.general"
         collapsible :default-open="true"
-        @accept="onAccept" @alias="onAlias" @dismiss="store.dismiss"
+        @accept="onAccept" @alias="onAlias" @remove-alias="onRemoveAlias"
+        @dismiss="store.dismiss"
       />
     </template>
 
@@ -98,6 +100,17 @@ async function onAliasConfirm(canonicalTagId) {
     toast({ text: `Alias failed: ${e.message}`, type: 'error' })
   }
 }
+
+// Undo the model-key→tag mapping behind an aliased suggestion. The store
+// reloads suggestions so the prediction reverts to its raw form; the applied
+// canonical tag (if any) stays, so no tag-rail reload is needed.
+async function onRemoveAlias(s) {
+  try {
+    await store.removeAlias(s)
+  } catch (e) {
+    toast({ text: `Remove alias failed: ${e.message}`, type: 'error' })
+  }
+}
 </script>
 
 <style scoped>