feat(gallery): OR/exclude tag filtering — light chips + advanced builder (#6b/c/d)

Cluster A, milestone #97. Completes the frontend of the structured tag filter
(backend landed in 23fab98).

#6b store: gallery.filter gains tag_or (OR-groups) + tag_exclude; one model,
serialized via tag_or (repeated key) + tag_not across activeFilterParam/
filterToQuery/applyFilterFromQuery/cloneFilter/loadSimilar; _resolveLabels
resolves names for every referenced id. useApi now appends array param values
as a repeated key (tag_or=a&tag_or=b).

#6c light editor (GalleryFilterBar): autocomplete pick → include chip; click a
chip body to flip include↔exclude (exclude = red minus); ✕ removes. An
"N OR-groups" chip + an Advanced button open the builder.

#6d advanced editor (TagQueryBuilder.vue + common/TagPicker.vue): AND-of-OR
group builder + NOT list. Unifies includes+OR-groups into one groups view,
splits back to tag_ids/tag_or on Apply so the URL stays compact. Writes the
same model the light chips edit.

Store serialization round-trip tests added.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XCUHUGQLrBrkgyk1t49kpX

frontend/src/components/common/TagPicker.vue

@@ -0,0 +1,68 @@
+<template>
+  <!-- Thin debounced tag-search autocomplete: emits `pick` with the chosen tag
+       and self-clears. Shared by the gallery's advanced tag-query builder; the
+       filter bar's own inline search predates this and also folds in artists. -->
+  <v-autocomplete
+    v-model="selected"
+    :items="items"
+    :loading="loading"
+    item-title="name" item-value="id"
+    no-filter hide-details density="compact" variant="outlined"
+    :placeholder="placeholder"
+    prepend-inner-icon="mdi-tag-plus-outline"
+    :aria-label="placeholder"
+    @update:search="onSearch"
+    @update:model-value="onPick"
+  >
+    <template #item="{ props: itemProps, item }">
+      <v-list-item v-bind="itemProps" :title="item.raw.name">
+        <template #subtitle>
+          {{ item.raw.fandom_name ? `character · ${item.raw.fandom_name}` : item.raw.kind }}
+        </template>
+      </v-list-item>
+    </template>
+    <template #no-data>
+      <v-list-item :title="searchedOnce ? 'No tags match' : 'Type to search tags'" />
+    </template>
+  </v-autocomplete>
+</template>
+
+<script setup>
+import { ref, onBeforeUnmount } from 'vue'
+import { useApi } from '../../composables/useApi.js'
+
+defineProps({ placeholder: { type: String, default: 'Add tag…' } })
+const emit = defineEmits(['pick'])
+
+const api = useApi()
+const selected = ref(null)
+const items = ref([])
+const loading = ref(false)
+const searchedOnce = ref(false)
+let debounce = null
+
+function onSearch (q) {
+  if (debounce) clearTimeout(debounce)
+  if (!q || !q.trim()) { items.value = []; return }
+  debounce = setTimeout(async () => {
+    loading.value = true
+    try {
+      items.value = (await api.get('/api/tags/autocomplete', { params: { q, limit: 10 } })) || []
+    } catch {
+      items.value = []
+    } finally {
+      loading.value = false
+      searchedOnce.value = true
+    }
+  }, 250)
+}
+
+function onPick (id) {
+  const tag = items.value.find((i) => i.id === id)
+  selected.value = null
+  items.value = []
+  if (tag) emit('pick', tag)
+}
+
+onBeforeUnmount(() => { if (debounce) clearTimeout(debounce) })
+</script>