docs: 合并性能分析报告并优化内存管理

将 performance-reporter.md 合入 memory-peak-analysis.md，统一分析文档。
代码优化包括：compact 峰值释放、GC 阈值触发、虚拟滚动参数调优、
HybridTransport 队列缩减、无界缓存加 LRU 淘汰、taskSummary 避免数组拷贝。

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

src/hooks/useVirtualScroll.ts

@@ -20,7 +20,7 @@ const DEFAULT_ESTIMATE = 3
  * Extra rows rendered above and below the viewport. Generous because real
  * heights can be 10x the estimate for long tool results.
  */
-const OVERSCAN_ROWS = 80
+const OVERSCAN_ROWS = 40
 /** Items rendered before the ScrollBox has laid out (viewportHeight=0). */
 const COLD_START_COUNT = 30
 /**
@@ -43,7 +43,7 @@ const SCROLL_QUANTUM = OVERSCAN_ROWS >> 1
  */
 const PESSIMISTIC_HEIGHT = 1
 /** Cap on mounted items to bound fiber allocation even in degenerate cases. */
-const MAX_MOUNTED_ITEMS = 300
+const MAX_MOUNTED_ITEMS = 200
 /**
  * Max NEW items to mount in a single commit. Scrolling into a fresh range
  * with PESSIMISTIC_HEIGHT=1 would mount 194 items at once (OVERSCAN_ROWS*2+