feat(v1.2): 体验升级 — 快捷键系统 + 标签拖拽 + SFTP拖拽上传 + 组件拆分 + 响应式

任务1: 全局快捷键管理器 — useKeyboardShortcuts hook
  Ctrl+Tab/Shift+Tab标签切换, Ctrl+1~9跳转, F11全屏, Ctrl+Shift+N新建标签

任务2: 标签拖拽排序 — tabStore.moveTab + TabBar HTML5 DnD
  不可变更新, 拖拽视觉反馈(opacity+指示线), 活跃标签底部accent-blue指示线

任务3: SFTP拖拽上传 + useSFTP调试清理
  FileListPanel拖拽覆盖层(Upload图标+虚线边框), 5个调试函数→createLogger,
  disconnect()正确调用IPC, 删除mock data

任务4: SFTP右键菜单完善 — 重命名/复制路径/属性/权限
  FilePropertiesDialog+ChmodDialog, sftpStat/sftpChmod IPC全栈实现

任务5-6: 侧边栏分组折叠动画 + 宽度可拖拽调整
  Grid 0fr→1fr折叠动画, ChevronRight旋转, resize handle 180~400px, settings记忆

任务7: 响应式布局 + 视觉优化V1~V5
  useMediaQuery hook, <800px侧边栏overlay模式, SFTP垂直堆叠, WelcomeView响应式grid

任务8: Loading/Skeleton骨架屏
  Skeleton/SkeletonLine/SkeletonCircle/SkeletonBlock + FileListSkeleton/SessionTreeSkeleton/TabContentSkeleton

任务9: 空状态设计
  EmptyState通用组件, SessionTree/FileListPanel/WelcomeView/SFTPView空状态引导

任务10: TerminalView组件拆分重构 711行→285行
  useTerminalConnection(300行) + useTerminalSearch(123行)
  + TerminalOverlay(98行) + TerminalSearchBar(74行)

33 files changed, 2682 insertions(+), 872 deletions(-)

src/stores/tabStore.ts

@@ -63,7 +63,11 @@ interface TabState {
   closeLeftTabs: (tabId: string) => Tab[]
   closeAllTabs: () => Tab[]
   activateTab: (tabId: string) => void
+  activateTabByIndex: (index: number) => void
+  switchToNextTab: () => void
+  switchToPrevTab: () => void
   updateTabTitle: (tabId: string, title: string) => void
+  moveTab: (fromIndex: number, toIndex: number) => void
   getTabById: (tabId: string) => Tab | undefined
 }
 
@@ -230,6 +234,31 @@ export const useTabStore = create<TabState>()(
           activeTabId: tabId,
         })
       },
+
+      activateTabByIndex: (index) => {
+        const { tabs } = get()
+        if (index < 0 || index >= tabs.length) return
+        const targetTab = tabs[index]
+        if (targetTab) {
+          get().activateTab(targetTab.id)
+        }
+      },
+
+      switchToNextTab: () => {
+        const { tabs, activeTabId } = get()
+        if (tabs.length <= 1) return
+        const currentIndex = tabs.findIndex(t => t.id === activeTabId)
+        const nextIndex = (currentIndex + 1) % tabs.length
+        get().activateTab(tabs[nextIndex].id)
+      },
+
+      switchToPrevTab: () => {
+        const { tabs, activeTabId } = get()
+        if (tabs.length <= 1) return
+        const currentIndex = tabs.findIndex(t => t.id === activeTabId)
+        const prevIndex = (currentIndex - 1 + tabs.length) % tabs.length
+        get().activateTab(tabs[prevIndex].id)
+      },
       
       updateTabTitle: (tabId, title) => {
         const { tabs } = get()
@@ -239,6 +268,29 @@ export const useTabStore = create<TabState>()(
         set({ tabs: updatedTabs })
       },
 
+      moveTab: (fromIndex, toIndex) => {
+        const { tabs, activeTabId } = get()
+        if (
+          fromIndex === toIndex ||
+          fromIndex < 0 ||
+          toIndex < 0 ||
+          fromIndex >= tabs.length ||
+          toIndex >= tabs.length
+        ) {
+          return
+        }
+        // Immutable reorder
+        const newTabs = [...tabs]
+        const [moved] = newTabs.splice(fromIndex, 1)
+        newTabs.splice(toIndex, 0, moved)
+        // Re-apply isActive based on activeTabId
+        const reordered = newTabs.map(t => ({
+          ...t,
+          isActive: t.id === activeTabId,
+        }))
+        set({ tabs: reordered })
+      },
+
       getTabById: (tabId) => {
         return get().tabs.find(t => t.id === tabId)
       },