feat(content): 修复服务并添加chapters/knowledge-points/questions模块

- database.ts 导出db常量替代getDb()函数

- env.ts JWT_SECRET/ES_URL/NEO4J_URL改optional加DEV_MODE

- neo4j.ts driver惰性创建+try/catch+connectionTimeout:3000

- health/lifecycle改用Drizzle原生查询

- textbooks.schema修复integer到int+导出NewTextbook类型

- 新建chapters/knowledge-points/questions三模块CRUD

- knowledge-points含Neo4j前置依赖图非阻塞查询

- content-init.sql创建4张表

端到端验证: textbooks/chapters/knowledge-points/questions全CRUD通过

services/content/src/chapters/chapters.controller.ts

@@ -0,0 +1,61 @@
+import {
+  Body,
+  Controller,
+  Delete,
+  Get,
+  Param,
+  Post,
+  Put,
+} from "@nestjs/common";
+import {
+  ChaptersService,
+  type CreateChapterInput,
+  type UpdateChapterInput,
+} from "./chapters.service.js";
+import type { Chapter } from "./chapters.schema.js";
+
+@Controller("chapters")
+export class ChaptersController {
+  constructor(private readonly service: ChaptersService) {}
+
+  @Post()
+  async create(
+    @Body() body: CreateChapterInput,
+  ): Promise<{ success: true; data: { id: string } }> {
+    const result = await this.service.createChapter(body);
+    return { success: true, data: result };
+  }
+
+  @Get("textbook/:textbookId")
+  async listByTextbook(
+    @Param("textbookId") textbookId: string,
+  ): Promise<{ success: true; data: Chapter[] }> {
+    const data = await this.service.listChaptersByTextbook(textbookId);
+    return { success: true, data };
+  }
+
+  @Get(":id")
+  async getById(
+    @Param("id") id: string,
+  ): Promise<{ success: true; data: Chapter }> {
+    const data = await this.service.getChapter(id);
+    return { success: true, data };
+  }
+
+  @Put(":id")
+  async update(
+    @Param("id") id: string,
+    @Body() body: UpdateChapterInput,
+  ): Promise<{ success: true; data: { success: true } }> {
+    await this.service.updateChapter(id, body);
+    return { success: true, data: { success: true } };
+  }
+
+  @Delete(":id")
+  async remove(
+    @Param("id") id: string,
+  ): Promise<{ success: true; data: { success: true } }> {
+    await this.service.deleteChapter(id);
+    return { success: true, data: { success: true } };
+  }
+}