feat(ui): presentation-chrome auto-hide Settings controls (#141 step 4)

HeadsCard gains a "Hide presentation chrome" section: on/off switch + "Hide
confidence" (presentation_auto_apply_threshold) + "Flag if content ≥"
(presentation_conflict_threshold), wired to MLSettings via patchSettings and
loaded on mount. Makes the step-4 sweep's thresholds operator-tunable
(config-in-UI). wip is called out as never auto-hidden.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CDgx8bQS5YrGRK76v8HUnM

frontend/src/components/settings/HeadsCard.vue

@@ -159,6 +159,42 @@
       </div>
     </div>
 
+    <!-- Presentation chrome auto-hide (#141) -->
+    <div class="fc-auto mt-6">
+      <div class="d-flex align-center mb-1" style="gap: 10px;">
+        <v-icon size="18" color="accent">mdi-image-off-outline</v-icon>
+        <span class="fc-section-h">Hide presentation chrome</span>
+        <v-switch
+          v-model="presentationEnabled" :loading="settingBusy" hide-details
+          density="compact" color="success" class="ml-auto"
+          @update:model-value="onTogglePresentation"
+        />
+      </div>
+      <p class="fc-muted text-body-2 mb-3">
+        Auto-hide banners and editor screenshots from the gallery once a head has
+        learned them (≥ {{ minPositives }} examples) and clears
+        {{ Math.round((presentationThresholdInput || 0) * 100) }}% confidence.
+        <code>wip</code> is never auto-hidden. If a hidden image also looks like
+        real content (≥ {{ Math.round((presentationConflictInput || 0) * 100) }}%
+        on a content tag), it's flagged in the Hidden view instead of buried.
+        Every auto-hide is reversible.
+      </p>
+      <div class="d-flex mb-3" style="gap: 12px;">
+        <v-text-field
+          v-model.number="presentationThresholdInput" label="Hide confidence"
+          type="number" min="0.5" max="0.999" step="0.01" density="compact"
+          hide-details style="max-width: 200px;" :disabled="settingBusy"
+          @change="onSavePresentation"
+        />
+        <v-text-field
+          v-model.number="presentationConflictInput" label="Flag if content ≥"
+          type="number" min="0" max="1" step="0.05" density="compact"
+          hide-details style="max-width: 200px;" :disabled="settingBusy"
+          @change="onSavePresentation"
+        />
+      </div>
+    </div>
+
     <!-- Performance / tuning -->
     <div v-if="metricsConcepts.length" class="mt-5">
       <div class="fc-section-h mb-1">How auto-apply is landing</div>
@@ -218,6 +254,11 @@ const autoStatus = ref(null)
 const metricsData = ref(null)
 let autoTimer = null
 
+// --- Presentation chrome auto-hide state (#141) ---
+const presentationEnabled = ref(true)
+const presentationThresholdInput = ref(0.90)
+const presentationConflictInput = ref(0.50)
+
 const autoRunning = computed(() => autoStatus.value?.running_id != null)
 const lastSweep = computed(() =>
   (autoStatus.value?.runs || []).find(r => r.status !== 'running') || null)
@@ -248,6 +289,9 @@ onMounted(async () => {
     autoEnabled.value = !!s.head_auto_apply_enabled
     autoPrecisionInput.value = s.head_auto_apply_precision ?? 0.97
     autoMinPosInput.value = s.head_auto_apply_min_positives ?? 30
+    presentationEnabled.value = s.presentation_auto_apply_enabled ?? true
+    presentationThresholdInput.value = s.presentation_auto_apply_threshold ?? 0.90
+    presentationConflictInput.value = s.presentation_conflict_threshold ?? 0.50
   } catch { /* non-fatal */ }
   await refresh()
   if (running.value) startPoll()
@@ -332,6 +376,32 @@ async function onSaveSettings() {
     settingBusy.value = false
   }
 }
+
+async function onTogglePresentation(val) {
+  settingBusy.value = true
+  try {
+    await mlSettings.patchSettings({ presentation_auto_apply_enabled: !!val })
+    toast({ text: val ? 'Chrome auto-hide on' : 'Chrome auto-hide off', type: 'success' })
+  } catch (e) {
+    presentationEnabled.value = !val   // revert the switch
+    toast({ text: `Could not update: ${e.message}`, type: 'error' })
+  } finally {
+    settingBusy.value = false
+  }
+}
+async function onSavePresentation() {
+  settingBusy.value = true
+  try {
+    await mlSettings.patchSettings({
+      presentation_auto_apply_threshold: Number(presentationThresholdInput.value),
+      presentation_conflict_threshold: Number(presentationConflictInput.value),
+    })
+  } catch (e) {
+    toast({ text: `Could not save: ${e.message}`, type: 'error' })
+  } finally {
+    settingBusy.value = false
+  }
+}
 function onPreview() { startSweep(true) }
 function onApplyNow() { startSweep(false) }
 async function startSweep(dryRun) {