feat(ml): clamp allowlist min_confidence to the tagger store floor

Consumer #4 of the store-floor change (#764). An allowlist tag can't
auto-apply more permissively than the ingest floor — predictions below
tagger_store_floor aren't stored, so a lower min_confidence behaves
identically to the floor. update_threshold now clamps to max(value, floor);
the AllowlistTable confidence input min-binds to the live floor and clamps
on edit. Keeps the stored threshold honest about actual apply behavior.

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

frontend/src/components/settings/AllowlistTable.vue

@@ -10,7 +10,7 @@
         <v-text-field
           :model-value="item.min_confidence" type="number"
           density="compact" hide-details style="max-width: 100px;"
-          min="0.05" max="1" step="0.05"
+          :min="floor" max="1" step="0.05"
           @update:model-value="(v) => onThreshold(item.tag_id, v)"
         />
       </template>
@@ -25,23 +25,32 @@
 </template>
 
 <script setup>
-import { onMounted } from 'vue'
+import { computed, onMounted } from 'vue'
 import { useAllowlistStore } from '../../stores/allowlist.js'
+import { useMLStore } from '../../stores/ml.js'
 
 const store = useAllowlistStore()
+const ml = useMLStore()
+// min_confidence can't be set below the tagger store floor — predictions
+// below it aren't stored, so a lower threshold would behave identically to
+// the floor. The backend clamps too (#764).
+const floor = computed(() => ml.settings?.tagger_store_floor ?? 0.70)
 const headers = [
   { title: 'Tag', key: 'tag_name', sortable: true },
   { title: 'Kind', key: 'tag_kind', sortable: true, width: 110 },
   { title: 'Min confidence', key: 'min_confidence', sortable: false, width: 140 },
   { title: '', key: 'actions', sortable: false, width: 60 }
 ]
-onMounted(() => store.load())
+onMounted(() => {
+  store.load()
+  if (!ml.settings) ml.loadSettings()
+})
 
 let debounce = null
 function onThreshold(tagId, value) {
   if (debounce) clearTimeout(debounce)
   debounce = setTimeout(() => {
-    const v = parseFloat(value)
+    const v = Math.max(parseFloat(value), floor.value)
     if (v > 0 && v <= 1) store.updateThreshold(tagId, v)
   }, 500)
 }