refactor(tags): unify suggestion source — one canonical DB-tag dropdown, drop dead raw/alias machinery (#154)

Every tag suggestion is a canonical DB tag now (tagging-v2 #114: heads + CCIP
score EXISTING concept tags). The pre-heads apparatus for model-predicted tags
that didn't exist in the DB — creates_new_tag / raw_name / via_alias, the
/suggestions/alias endpoint + add_alias_and_accept, AliasPickerDialog, and the
store's aliasAccept/removeAlias — was dead and is removed.

The type-to-add dropdown was TWO row sources (server autocomplete + the image's
ML suggestions) merged with a dedup that dropped the %-bearing suggestion row
when the debounced server hit landed — the operator's "confidence % flickers
then vanishes". Now it's ONE list of DB-tag matches, each annotated with the
model's confidence (join by canonical_tag_id) when the tag was scored for this
image. No dedup, no flicker; picking a suggested tag still records acceptance
via TagPanel.findPending.

Single per-image fetch: score_image now reports above_threshold per row
(computed vs the head's own suggest cut, separate from the inclusion floor), so
the rail makes ONE min=0 request and derives the panel (above_threshold) and the
dropdown (all, text-filtered) client-side — the two /suggestions calls collapse
to one. Manual "Create 'X' as <kind>" (novel typed names) is unchanged; the
alias table + tag-side alias admin + auto-apply alias matching are untouched.

Tests: gate/serializer assertions updated (above_threshold; dropped dead-field
+ alias-endpoint checks); frontend spec seeds via the single load and covers the
byCategory/aboveByCategory split.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CgZP9v2otxVJymiYsnVuMy

frontend/src/components/modal/SuggestionItem.vue

@@ -11,10 +11,6 @@
       {{ suggestion.display_name }}
       <span v-if="suggestion.rejected" class="fc-suggestion__rejected-tag"
         title="You rejected this for this image — un-reject to recover">rejected</span>
-      <span v-else-if="suggestion.creates_new_tag" class="fc-suggestion__new"
-        title="No matching tag yet — accepting creates it">+ new</span>
-      <span v-else-if="suggestion.via_alias" class="fc-suggestion__alias"
-        :title="`Mapped from the tagger's “${suggestion.raw_name}” via an alias`">alias</span>
     </span>
     <span class="fc-suggestion__score">{{ scorePct }}</span>
     <!-- Green ✓ / red ✗ pair (operator-asked 2026-06-28) mirrors the eval
@@ -46,40 +42,14 @@
         @click="$emit('dismiss', suggestion)"
       ><v-icon size="16">mdi-close</v-icon></button>
     </div>
-    <!-- Modal-safe kebab is baked into KebabMenu (this row lives in the
-         teleported image modal — #711). Only rendered when an alias action
-         applies — dismiss now lives on the red ✗, so a centroid hit with no
-         alias option has no menu. -->
-    <KebabMenu
-      v-if="hasMenu"
-      class="fc-suggestion__menu" size="small" variant="outlined"
-      :label="`More actions for ${suggestion.display_name}`"
-    >
-      <!-- Alias is a tagger-prediction remap, so only offer it for tagger
-           suggestions with a raw model key that aren't already aliased.
-           Centroid hits (raw_name null) have nothing to alias. -->
-      <v-list-item
-        v-if="suggestion.raw_name && !suggestion.via_alias"
-        @click="$emit('alias', suggestion)"
-      >
-        <v-list-item-title>Treat as alias for…</v-list-item-title>
-      </v-list-item>
-      <v-list-item
-        v-if="suggestion.via_alias"
-        @click="$emit('remove-alias', suggestion)"
-      >
-        <v-list-item-title>Remove alias</v-list-item-title>
-      </v-list-item>
-    </KebabMenu>
   </div>
 </template>
 
 <script setup>
 import { computed, inject } from 'vue'
-import KebabMenu from '../common/KebabMenu.vue'
 
 const props = defineProps({ suggestion: { type: Object, required: true } })
-defineEmits(['accept', 'alias', 'remove-alias', 'dismiss', 'undismiss'])
+defineEmits(['accept', 'dismiss', 'undismiss'])
 
 // #1206: on hover, tell the image viewer which crop produced this suggestion so
 // it highlights that region. Provided by ImageViewer/Explore; a no-op elsewhere.
@@ -92,12 +62,6 @@ function onLeave () {
 }
 
 const scorePct = computed(() => `${Math.round(props.suggestion.score * 100)}%`)
-// Kebab now only carries alias actions: show it when this suggestion can be
-// aliased (raw model key, not yet aliased) or is already aliased (so it can be
-// un-aliased). Centroid hits (no raw_name, no alias) have an empty menu → hide.
-const hasMenu = computed(() =>
-  Boolean(props.suggestion.raw_name) || Boolean(props.suggestion.via_alias)
-)
 </script>
 
 <style scoped>
@@ -119,26 +83,6 @@ const hasMenu = computed(() =>
   color: rgb(var(--v-theme-on-surface));
   overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
 }
-.fc-suggestion__new {
-  display: inline-block;
-  font-size: 10px; font-weight: 600;
-  color: rgb(var(--v-theme-accent));
-  background: rgba(var(--v-theme-accent), 0.12);
-  border: 1px solid rgb(var(--v-theme-accent), 0.4);
-  padding: 1px 6px; border-radius: 999px;
-  margin-left: 6px;
-  text-transform: uppercase; letter-spacing: 0.04em;
-}
-.fc-suggestion__alias {
-  display: inline-block;
-  font-size: 10px; font-weight: 600;
-  color: rgb(var(--v-theme-on-surface-variant));
-  background: rgb(var(--v-theme-surface-light));
-  border: 1px solid rgb(var(--v-theme-surface-light));
-  padding: 1px 6px; border-radius: 999px;
-  margin-left: 6px;
-  text-transform: uppercase; letter-spacing: 0.04em;
-}
 .fc-suggestion__score {
   flex: 0 0 auto; min-width: 38px; text-align: right;
   font-size: 11px;
@@ -166,10 +110,6 @@ const hasMenu = computed(() =>
   background: transparent; color: rgb(var(--v-theme-on-surface-variant));
   border: 1px solid rgb(var(--v-theme-on-surface-variant), 0.5);
 }
-.fc-suggestion__menu {
-  flex: 0 0 auto;
-}
-
 /* Rejected state: the row stays put (recovery), dimmed + red-edged so it
    reads as "handled, negative" without shouting over live suggestions. */
 .fc-suggestion--rejected {