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/query.ts

@@ -529,6 +529,16 @@ async function* queryLoop(
       querySource,
     )
     messagesForQuery = microcompactResult.messages
+    // Release original strings from contentReplacementState.replacements for
+    // tool results whose content was replaced with the cleared message.
+    if (microcompactResult.clearedToolUseIds?.length) {
+      const replacements = toolUseContext?.contentReplacementState?.replacements
+      if (replacements) {
+        for (const id of microcompactResult.clearedToolUseIds) {
+          replacements.delete(id)
+        }
+      }
+    }
     // For cached microcompact (cache editing), defer boundary message until after
     // the API response so we can use actual cache_deleted_input_tokens.
     // Gated behind feature() so the string is eliminated from external builds.