fix: 修复长时间运行会话的内存泄漏问题

/clear 时释放 STATE 中保存的大块数据（API 请求/分类器请求/模型统计），
全屏模式增加 500 条消息上限防止无限增长，修复 progress 消息去重逻辑
避免交错消息导致重复累积（观察到 13k+ 条目/1GB+ 堆）。

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

src/commands/clear/conversation.ts

@@ -10,6 +10,10 @@ import {
   getOriginalCwd,
   getSessionId,
   regenerateSessionId,
+  resetCostState,
+  setLastAPIRequest,
+  setLastAPIRequestMessages,
+  setLastClassifierRequests,
 } from '../../bootstrap/state.js'
 import type { SDKStatusMessage } from '../../entrypoints/sdk/coreTypes.js'
 import {
@@ -144,6 +148,14 @@ export async function clearConversation({
   // tracking) is retained so those agents keep functioning.
   clearSessionCaches(preservedAgentIds)
 
+  // Clear large STATE-held data that outlives the message array.
+  // lastAPIRequestMessages can hold the full post-compaction conversation
+  // (hundreds of KB–MB) for /share; resetCostState clears modelUsage.
+  setLastAPIRequest(null)
+  setLastAPIRequestMessages(null)
+  setLastClassifierRequests(null)
+  resetCostState()
+
   setCwd(getOriginalCwd())
   readFileState.clear()
   discoveredSkillNames?.clear()