feat(ui): streamline workspace settings and remove sharing

Unify compact workspace controls and panel transitions, move directory actions into the context menu, and remove backlink UI.

Reorganize settings with searchable sections, per-setting resets, shortcut search, and accurate save feedback.

Remove sharing UI, APIs, authentication helpers, and storage code; provide a transactional cleanup script with retirement tests. Reject directories during orphan image cleanup and cover mixed-batch preservation.

web/src/app/SettingRow.vue

@@ -0,0 +1,21 @@
+<script setup lang="ts">
+import { computed } from 'vue'
+import Icon from './Icon.vue'
+import { SETTING_ITEMS, type SettingId } from './settingsCatalog'
+const props = defineProps<{ id: SettingId; control?: string; resettable?: boolean }>()
+defineEmits<{ reset: [] }>()
+const item = computed(() => SETTING_ITEMS[props.id])
+</script>
+
+<template>
+  <div :id="'rm-setting-' + id" class="rm-setting" tabindex="-1">
+    <div class="rm-setting-info">
+      <component :is="control ? 'label' : 'span'" :for="control" class="rm-setting-label">{{ item.title }}</component>
+      <p>{{ item.description }}</p>
+    </div>
+    <div class="rm-setting-control">
+      <slot />
+      <button v-if="resettable" class="rm-icon-btn rm-setting-reset" :title="'重置' + item.title" :aria-label="'重置' + item.title" @click="$emit('reset')"><Icon name="restore" /></button>
+    </div>
+  </div>
+</template>