fix: 内存优化 — 预测性 compact 阈值、增量 lookups orphaned 修复、deferred slice 引用优化

- P0: REPL.tsx 用 useMemo 包裹 deferred messages slice，避免每次渲染创建新数组引用导致不必要的后台重渲染
- P1: 预测性 compact 阈值改用 effectiveContextWindow - growth，消除与 autocompact buffer 的双重预留；TOOL_RESULT_GROWTH_ESTIMATE 从 20K 降至 15K
- P2: 增量 lookups 增加 lastAssistantMsgId 一致性检查和 orphaned server_tool_use/mcp_tool_use 扫描，防止 UI 永久 loading
- P3: reactiveCompact 类型断言改为直接使用 'compact' 字面量
- docs: CLAUDE.md 统一使用 precheck 替代分散的 typecheck/lint/test 命令

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

src/screens/REPL.tsx

@@ -1566,7 +1566,15 @@ export function REPL({
   // Deferred messages for the Messages component — renders at transition
   // priority so the reconciler yields every 5ms, keeping input responsive
   // while the expensive message processing pipeline runs.
-  const deferredMessages = useDeferredValue(messages);
+  // Cap at 500 messages to limit memory double-buffering. The bypass
+  // at display-time uses sync messages during streaming and non-loading,
+  // so this cap only affects reduced-motion scenarios.
+  const DEFERRED_CAP = 500;
+  const cappedMessages = React.useMemo(
+    () => (messages.length > DEFERRED_CAP ? messages.slice(-DEFERRED_CAP) : messages),
+    [messages],
+  );
+  const deferredMessages = useDeferredValue(cappedMessages);
   const deferredBehind = messages.length - deferredMessages.length;
   if (deferredBehind > 0) {
     logForDebugging(