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)

packages/rpa-core/src/engine/registry.ts

@@ -0,0 +1,24 @@
+import type { CapabilityHandler } from "./types";
+
+const handlers = new Map<string, CapabilityHandler>();
+
+export function register(ids: string | string[], handler: CapabilityHandler): void {
+  const list = Array.isArray(ids) ? ids : [ids];
+  for (const id of list) handlers.set(id, handler);
+}
+
+export function getHandler(id: string): CapabilityHandler | undefined {
+  return handlers.get(id);
+}
+
+export function hasCapability(id: string): boolean {
+  return handlers.has(id);
+}
+
+export function capabilityIds(): string[] {
+  return [...handlers.keys()];
+}
+
+export function capabilityCount(): number {
+  return handlers.size;
+}