feat(phash): ImportFiltersForm exposes phash_threshold

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/components/settings/ImportFiltersForm.vue

@@ -41,6 +41,14 @@
             :disabled="!local.skip_single_color" @end="save"
           />
         </v-col>
+        <v-col cols="12" sm="6">
+          <v-text-field
+            v-model.number="local.phash_threshold"
+            label="Perceptual-hash threshold" type="number" min="0"
+            density="compact" hide-details @blur="save"
+          />
+          <div class="fc-help">Higher = looser near-duplicate matching.</div>
+        </v-col>
       </v-row>
       <v-alert v-if="store.settingsError" type="error" variant="tonal" class="mt-2" closable>
         {{ store.settingsError }}
@@ -60,7 +68,8 @@ const store = useImportStore()
 const local = reactive({
   min_width: 0, min_height: 0,
   skip_transparent: false, transparency_threshold: 0.9,
-  skip_single_color: false, single_color_threshold: 0.95
+  skip_single_color: false, single_color_threshold: 0.95,
+  phash_threshold: 10
 })
 
 watch(() => store.settings, (s) => { if (s) Object.assign(local, s) }, { immediate: true })
@@ -69,3 +78,11 @@ async function save() {
   await store.patchSettings({ ...local })
 }
 </script>
+
+<style scoped>
+.fc-help {
+  font-size: 12px;
+  color: rgb(var(--v-theme-on-surface-variant));
+  margin-top: 2px;
+}
+</style>