feat: 正式启用 auto mode (#307)

* fix: 修复settings.json内存状态溢出的问题

* fix: 修复auto mode gate check未处理的promise rejection

在 bypassPermissionsKillswitch.ts 的 useKickOffCheckAndDisableAutoModeIfNeeded
中，void fire-and-forget 调用缺少 .catch() 处理，导致 verifyAutoModeGateAccess
失败时产生 unhandled promise rejection。同时移除 permissionSetup.ts 中冗余的
null check。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: 开放 auto mode 和 bypass mode 给所有用户

通过 Shift+Tab 统一循环：default → acceptEdits → plan → auto → bypassPermissions → default

- 移除 USER_TYPE 分支判断，所有用户使用同一循环路径
- isBypassPermissionsModeAvailable 始终为 true
- isAutoModeAvailable 初始化直接为 true
- 移除 AutoModeOptInDialog 确认流程
- 简化 isAutoModeGateEnabled 仅保留快模式熔断器
- 简化 verifyAutoModeGateAccess 仅检查快模式
- 移除 GrowthBook/Statsig 远程门控
- bypass permissions killswitch 改为 no-op
- 新增 24 个测试覆盖循环逻辑和门控不变量

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: 为sideQuery添加Langfuse追踪

sideQuery 绕过了 claude.ts 的主 API 路径，导致所有走 sideQuery 的调用
（auto mode classifier、permission explainer、session search 等）都没有
Langfuse 记录。现在为每次 sideQuery 调用创建独立 trace 并记录 LLM observation，
未配置 Langfuse 时全部 no-op。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: ACP availableModes 补齐 bypassPermissions 并修正测试 import 路径

- ACP agent availableModes 按条件包含 bypassPermissions（非 root/sandbox）
- 顺序对齐 REPL 循环：default → acceptEdits → plan → auto → bypassPermissions
- 新增 2 个测试验证 availableModes 包含 bypassPermissions 及模式切换
- 修正 getNextPermissionMode.test.ts 和 permissionSetup.test.ts 的 import 路径

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

src/state/onChangeAppState.ts

@@ -17,7 +17,6 @@ import {
   notifySessionMetadataChanged,
   type SessionExternalMetadata,
 } from '../utils/sessionState.js'
-import { updateSettingsForSource } from '../utils/settings/settings.js'
 import type { AppState } from './AppStateStore.js'
 
 // Inverse of the push below — restore on worker restart.
@@ -91,23 +90,11 @@ export function onChangeAppState({
     notifyPermissionModeChanged(newMode)
   }
 
-  // mainLoopModel: remove it from settings?
-  if (
-    newState.mainLoopModel !== oldState.mainLoopModel &&
-    newState.mainLoopModel === null
-  ) {
-    // Remove from settings
-    updateSettingsForSource('userSettings', { model: undefined })
-    setMainLoopModelOverride(null)
-  }
-
-  // mainLoopModel: add it to settings?
-  if (
-    newState.mainLoopModel !== oldState.mainLoopModel &&
-    newState.mainLoopModel !== null
-  ) {
-    // Save to settings
-    updateSettingsForSource('userSettings', { model: newState.mainLoopModel })
+  // mainLoopModel: session-scoped only (do NOT persist to userSettings).
+  // Writing to settings.json would leak model changes into other running
+  // sessions (anthropics/claude-code#37596). Each process keeps its own
+  // model override in memory via setMainLoopModelOverride.
+  if (newState.mainLoopModel !== oldState.mainLoopModel) {
     setMainLoopModelOverride(newState.mainLoopModel)
   }