feat(device-sync): manifest, cancel, font picker + sync status fix

- Write psysonic-sync.json to device after sync/deletions; auto-import
  on folder select when localStorage is empty (cross-platform handoff)
- Add cancel button during active sync: AtomicBool flag per job,
  tasks bail after acquiring semaphore, cancelled state in UI
- Fix sync status staying "pending": normalize template path separators
  to OS separator (Windows: '/' → '\') so compute_sync_paths and
  list_device_dir_files produce matching strings for Set comparison
- Add Geist and JetBrains Mono as variable fonts; font picker collapsible
- Fix device mount detection on Windows: removable drive letters (E:\)
  were incorrectly skipped alongside system roots; strip \?\ prefix
  from canonicalized paths before mount-point comparison

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/locales/zh.ts

@@ -1091,6 +1091,8 @@ export const zhTranslation = {
     fetchError: '从服务器加载曲目失败。',
     syncComplete: '同步完成。',
     dismiss: '关闭',
+    cancelSync: '取消',
+    syncCancelled: '同步已取消（已传输 {{done}} / {{total}}）。',
     colName: '名称',
     colType: '类型',
     colStatus: '状态',
@@ -1100,6 +1102,7 @@ export const zhTranslation = {
     deleteFromDevice: '标记为删除（{{count}}）',
     confirmDelete: '从设备删除 {{count}} 个项目：{{names}}？',
     deleteComplete: '已从设备删除 {{count}} 个项目。',
+    manifestImported: '已从设备清单导入 {{count}} 个来源。',
     statusSynced: '已同步',
     statusPending: '待处理',
     statusDeletion: '删除中',