docs: 交付文档、维护指引与端到端回归

补齐 README、开发计划、维护交接与 E2E 用例，执行最终验收。

e2e/src/fakes/mcp.ts

@@ -0,0 +1,22 @@
+import type { APIRequestContext } from '@playwright/test'
+import { env } from '../env'
+
+export interface McpRequest {
+  at: string
+  authorization: string | null
+  rpcMethod: string | null
+}
+
+/** Test-side client for services/fake-mcp: what reached the MCP server. */
+export class FakeMcp {
+  readonly url = `${env.fakeMcpUrl}/mcp`
+  private readonly request: APIRequestContext
+
+  constructor(request: APIRequestContext) {
+    this.request = request
+  }
+
+  async requests(): Promise<McpRequest[]> {
+    return (await (await this.request.get(`${env.fakeMcpUrl}/__requests`)).json()) as McpRequest[]
+  }
+}