阶段1-rpa-core建包: engine+31个纯Node能力迁入packages/rpa-core, 领域类型单一源化, createEngine工厂收拢模块级状态

- engine/(registry/types/runtime/expression)物理迁入包, 解耦shared/types(域类型归包, 宿主type-only re-export)
- 31个纯Node能力+27个测试迁入包; 宿主留守Electron/浏览器/AI依赖能力, index.ts经@rpa/core/capabilities拉起
- 新增createEngine()/defaultEngine: excel缓存/Excel句柄/db连接/FTP客户端/OCR实例/拟真设置挂引擎实例
- remaining-core子流程依赖改为host-bridge注入, 包内不再import宿主flows
- 宿主main/index.ts启动时注入子流程源; electron-vite/vitest/tsconfig配@rpa/core源码别名
- 验证: typecheck绿, 快照909个id diff为零, 332测试过(2个桌面冒烟因会话无交互SetForegroundWindow被拒, 环境阻塞)

src/main/capabilities/browser.ts

@@ -1,7 +1,7 @@
-import { register } from "../engine/registry";
-import { RuntimeError } from "../engine/types";
+import { register } from "@rpa/core";
+import { RuntimeError } from "@rpa/core";
 import { browserSession, externalBrowserSession } from "../browser/session";
-import type { BrowserLike, RunContext } from "../engine/types";
+import type { BrowserLike, RunContext } from "@rpa/core";
 
 async function session(ctx: RunContext): Promise<BrowserLike> {
   if (!ctx.browser) ctx.browser = await browserSession();