fix: 0.9.1 快照收尾修复与稳健性增强 - 快照目录对归一化匹配（Windows同目录异写不误拦、与scanCacheStore同款逻辑双向同步）、截断结果保存快照拦截提示（防对照新文件误报）、folder:scan IPC校验抽scanIpc纯逻辑模块单测全覆盖（缓存源选择惰性读盘）、对照模式导出报告附变迁对照表（三格式当前/基线状态与大小、标签收敛SNAPSHOT_CHANGE_LABEL共享映射、E2E对照导出写盘断言）、顶层ErrorBoundary渲染兜底（错误面板一键重载防白屏）、文档四件套同步

src/main/index.ts

@@ -6,7 +6,7 @@ import fs from 'fs'
 import { parseState, clampBounds, type AppState } from './windowState'
 import { decodeText, type DecodeResult } from './decode'
 import { scanFolders, SEMANTIC_MAX_BYTES, type ScanCacheEntry } from './folderScan'
-import { isIgnoreRulesArray } from './ignoreRules'
+import { resolveScanArgs } from './scanIpc'
 import {
   parseScanCacheStore,
   putScanCache,
@@ -313,28 +313,12 @@ ipcMain.handle(
     ignoreRules?: unknown
   ) => {
     try {
-      // 增量缓存防御性校验：仅接受数组形态（渲染端从上次扫描结果携带，损坏即不沿用）
-      const cache =
-        Array.isArray(previous) && previous.every(
-          (c) =>
-            typeof c === 'object' &&
-            c !== null &&
-            typeof (c as ScanCacheEntry).rel === 'string' &&
-            typeof (c as ScanCacheEntry).status === 'string'
-        )
-          ? (previous as ScanCacheEntry[])
-          : undefined
-      // 渲染端未携带内存缓存时（跨会话首次扫描），尝试注入 userData 落盘的持久化缓存
-      let prev = cache
-      if (prev === undefined) {
-        const stored = getScanCache(loadScanCacheStore(), leftDir, rightDir)
-        if (stored !== null && stored.length > 0) prev = stored
-      }
-      // 忽略规则防御性校验：仅接受字符串数组形态（渲染端从偏好携带，损坏即忽略）
-      const ignore = isIgnoreRulesArray(ignoreRules) ? ignoreRules : undefined
+      // 入参防御性校验与增量缓存源选择（内存缓存优先，未携带/非法回退 userData 落盘缓存，惰性读盘）
+      const args = resolveScanArgs(previous, ignoreRules, () =>
+        getScanCache(loadScanCacheStore(), leftDir, rightDir)
+      )
       const result = await scanFolders(leftDir, rightDir, {
-        ...(prev ? { previous: prev } : {}),
-        ...(ignore ? { ignore } : {}),
+        ...args,
         ...(semantic
           ? {
               // 语义判等解码复用解码 worker（大缓冲后台解码，与文件打开共用同一管线）