feat: 支持 AI 设计项目多会话交互

需求：用户可在同一设计项目中新建和切换会话，任务列表保持项目级共享。

实现：
- 增加会话选择、新建入口及本地数据迁移
- Conversation 独立消息、Brief、Quote 与流式状态
- 保留项目任务并修复 Task revision 与 ABA 异步竞态
- 保持 Enter 发送、Shift+Enter 换行及 IME 保护

electron/main/index.ts

@@ -32,10 +32,6 @@ import { logger } from '../utils/logger';
 import { warmupNetworkOptimization } from '../utils/uv-env';
 import { resolvePythonRuntime } from '../utils/python-runtime';
 import { initTelemetry } from '../utils/telemetry';
-import {
-  getOrCreateAgentGatewaySessionClientId,
-  rotateAgentGatewaySessionClientId,
-} from '../utils/store';
 
 import { isQuitting, setQuitting } from './app-state';
 import { applyProxySettings } from './proxy';
@@ -425,12 +421,7 @@ async function initialize(): Promise<void> {
   });
   const imageWorkspace = localImageWorkspaceEnabled
     ? new LocalImageWorkspace({ userDataDir: app.getPath('userData') })
-    : new WorksSquareDesignWorkspace({
-        eventSessionClientIdStore: {
-          getOrCreate: getOrCreateAgentGatewaySessionClientId,
-          rotate: rotateAgentGatewaySessionClientId,
-        },
-      });
+    : new WorksSquareDesignWorkspace();
   imageWorkspaceModule = imageWorkspace;
   if (localImageWorkspaceEnabled) {
     logger.info('AI painting workspace is using local development storage');