已完成迁移验收和清理。

删除全部 Node.js 后端、.mjs 测试、辅助脚本、package*.json、node_modules 和迁移对照工具。
浏览器前端保留并迁入 [Eis.Web/wwwroot](C:/Users/BI/Documents/EIS-dotnet/src/Eis.Web/wwwroot/index.html)，统一改为 .js 模块。
修复一个隐藏遗漏：.NET 仍依赖 schema.mjs，且 MySQL 结构解析可能被转义反引号截断。现已改为原生 [SQLite SQL](C:/Users/BI/Documents/EIS-dotnet/src/Eis.Infrastructure/Data/Schema.sqlite.sql) 和 [MySQL SQL](C:/Users/BI/Documents/EIS-dotnet/src/Eis.Infrastructure/Data/Schema.mysql.sql) 资源。
更新了 [DatabaseInitializer.cs](C:/Users/BI/Documents/EIS-dotnet/src/Eis.Infrastructure/Data/DatabaseInitializer.cs)、项目配置、README 和迁移文档。
data 目录和现有数据库未修改；测试仅使用系统临时 SQLite 数据库。

src/Eis.Web/wwwroot/js/client/api.js

@@ -0,0 +1,34 @@
+const pendingReads = new Map();
+
+async function request(path, options) {
+  const binaryBody = options.body instanceof ArrayBuffer || options.body instanceof Blob || options.body instanceof FormData;
+  const response = await fetch(path, {
+    credentials: 'same-origin',
+    headers: { ...(options.body && !binaryBody ? { 'Content-Type': 'application/json' } : {}), ...options.headers },
+    ...options,
+    body: options.body && typeof options.body !== 'string' && !binaryBody ? JSON.stringify(options.body) : options.body
+  });
+  const type = response.headers.get('content-type') || '';
+  const data = type.includes('application/json') ? await response.json() : await response.text();
+  if (!response.ok) {
+    const error = new Error(data?.message || '操作未完成，请稍后重试');
+    error.status = response.status;
+    throw error;
+  }
+  return data;
+}
+
+export function api(path, options = {}) {
+  const method = String(options.method || 'GET').toUpperCase();
+  if (method !== 'GET' || options.body != null || options.signal) return request(path, options);
+
+  // A quick double click or repeated render must not download and parse the
+  // same large JSON response more than once while the first request is active.
+  const key = String(path);
+  if (pendingReads.has(key)) return pendingReads.get(key);
+  const loading = request(path, options).finally(() => {
+    if (pendingReads.get(key) === loading) pendingReads.delete(key);
+  });
+  pendingReads.set(key, loading);
+  return loading;
+}