fix: 内存优化 — FileReadTool 100KB 上限、lookups 缓存、microcompact 替换清理

- FileReadTool maxResultSizeChars 从 Infinity 改为 100KB，大文件持久化到磁盘
- Messages.tsx 新增 computeMessageStructureKey 缓存，流式 delta 时跳过 8 个 Map/Set 重建
- microcompact 返回 clearedToolUseIds，query.ts 消费后清理 replacements Map 释放原始字符串
- 更新内存分析报告 Round 5 和 file-operations 文档

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/services/compact/microCompact.ts

@@ -217,6 +217,10 @@ export type MicrocompactResult = {
   compactionInfo?: {
     pendingCacheEdits?: PendingCacheEdits
   }
+  // Tool use IDs whose content was replaced with the cleared message.
+  // Callers should remove these from contentReplacementState.replacements
+  // to release the original strings from memory.
+  clearedToolUseIds?: string[]
 }
 
 /**
@@ -528,5 +532,5 @@ function maybeTimeBasedMicrocompact(
     notifyCacheDeletion(querySource)
   }
 
-  return { messages: result }
+  return { messages: result, clearedToolUseIds: [...clearSet] }
 }