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/utils/plans.ts

@@ -10,7 +10,11 @@ import type {
   SystemFileSnapshotMessage,
   UserMessage,
 } from 'src/types/message.js'
-import { getPlanSlugCache, getSessionId } from '../bootstrap/state.js'
+import {
+  getPlanSlugCache,
+  getSessionId,
+  setPlanSlugCacheEntry,
+} from '../bootstrap/state.js'
 import { EXIT_PLAN_MODE_V2_TOOL_NAME } from '@claude-code-best/builtin-tools/tools/ExitPlanModeTool/constants.js'
 import { getCwd } from './cwd.js'
 import { logForDebugging } from './debug.js'
@@ -43,7 +47,7 @@ export function getPlanSlug(sessionId?: SessionId): string {
         break
       }
     }
-    cache.set(id, slug!)
+    setPlanSlugCacheEntry(id, slug!)
   }
   return slug!
 }
@@ -52,7 +56,7 @@ export function getPlanSlug(sessionId?: SessionId): string {
  * Set a specific plan slug for a session (used when resuming a session)
  */
 export function setPlanSlug(sessionId: SessionId, slug: string): void {
-  getPlanSlugCache().set(sessionId, slug)
+  setPlanSlugCacheEntry(sessionId, slug)
 }
 
 /**

src/utils/taskSummary.ts

@@ -44,9 +44,13 @@ export function maybeGenerateTaskSummary(
     if (!messages || messages.length === 0) return
 
     // Extract a short status from the most recent assistant message
-    const lastAssistant = [...messages]
-      .reverse()
-      .find(m => m.type === 'assistant')
+    let lastAssistant: (typeof messages)[0] | undefined
+    for (let i = messages.length - 1; i >= 0; i--) {
+      if (messages[i]!.type === 'assistant') {
+        lastAssistant = messages[i]
+        break
+      }
+    }
 
     let status: 'busy' | 'idle' = 'busy'
     let waitingFor: string | undefined