Add napcat-rpc package with deep RPC

Introduce a new napcat-rpc package implementing a deep-proxy RPC system. Adds client (createDeepProxy, proxy helpers), server (RpcServer, createRpcServer), serializer (serialize/deserialize, callback registry), and transport layers (LocalTransport, MessageTransport, message server handler), plus an easy API (createRpcPair, mockRemote, createServer, createClient). Includes TypeScript types, tsconfig and package.json. Wire-up: add package alias in napcat-schema vite config and add napcat-rpc dependency to napcat-test along with comprehensive rpc tests.

packages/napcat-test/vitest.config.ts

@@ -8,6 +8,7 @@ export default defineConfig({
   },
   resolve: {
     alias: {
+      '@/napcat-rpc': resolve(__dirname, '../napcat-rpc'),
       '@/napcat-image-size': resolve(__dirname, '../napcat-image-size'),
       '@/napcat-test': resolve(__dirname, '.'),
       '@/napcat-common': resolve(__dirname, '../napcat-common'),