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/shared/constants.ts

@@ -1,5 +1,5 @@
 // 共享常量 — 主进程和渲染进程共用
-export const APP_VERSION = 'v0.3.7'
+export const APP_VERSION = 'v0.3.8'
 export const MAX_FILE_SIZE = 20 * 1024 * 1024 // 20MB
 export const ALLOWED_EXTENSIONS = ['.md', '.markdown', '.txt'] as const
 export const SKIP_DIRS = new Set([