chore: bump version to 0.3.8

Code audit fixes:
- CRITICAL: reorder Markdown pipeline (fixImages before sanitize)
- CRITICAL: fix path prefix separator check
- BLOCKING: remove duplicate useEffect in Editor
- BLOCKING: skip onChange when content unchanged
- BLOCKING: optimize Sidebar re-render with useMemo
- HIGH: cleanup FileWatcher polling intervals
- HIGH: improve validatePath segment check
- HIGH: fix isExternalUpdate race with counter
- HIGH: add will-navigate / setWindowOpenHandler
- HIGH: explicit strip in sanitize schema
- MEDIUM: random temp file suffix instead of Date.now()
- MEDIUM/LOW: add IndexedDB error boundaries
- LOW: support UTF-16 BOM detection

src/renderer/components/Sidebar/Sidebar.tsx

@@ -18,7 +18,9 @@ const norm = (p: string) => p.replace(/[/\\]+$/, '').replace(/\\/g, '/')
 export const Sidebar = React.memo(function Sidebar() {
   const tabs = useTabStore(s => s.tabs)
   const activeTabId = useTabStore(s => s.activeTabId)
-  const activeTab = useTabStore(s => s.getActiveTab())
+  // B-03: 用 activeTabId + tabs 推导 activeTab 而非 s.getActiveTab()，
+  // 后者每次返回新对象引用导致 Zustand 无条件重渲染
+  const activeTab = useMemo(() => tabs.find(t => t.id === activeTabId) ?? null, [tabs, activeTabId])
   const switchToTab = useTabStore(s => s.switchToTab)
   const createTab = useTabStore(s => s.createTab)
   const rootPath = useSidebarStore(s => s.rootPath)