refactor: 重构项目目录与代码结构，清理冗余文件

本次提交进行了大规模的项目结构调整：
1. 调整文件目录归属，将模块代码按功能域重新组织
2. 删除多处冗余的DTO、实体类和模块文件
3. 统一了常量、装饰器、工具类的存放位置
4. 修复了`.gitignore`的日志目录匹配规则
5. 新增了健康检查、认证、用户、剧集、订单等核心业务模块

src/users/users.service.ts

@@ -0,0 +1,172 @@
+import { Injectable, NotFoundException, Optional } from "@nestjs/common";
+import { InjectDataSource } from "@nestjs/typeorm";
+import { DataSource } from "typeorm";
+import { PaginatedResponse } from "../../common/dto/paginated-response.dto";
+import { User } from "./entities/user.entity";
+import { UserRecord } from "./interfaces/user-record.interface";
+
+interface UpsertTikTokUserInput {
+    tiktokOpenId: string;
+    tiktokUnionId?: string;
+    nickname?: string;
+    avatarUrl?: string;
+}
+
+interface PaginationInput {
+    page: number;
+    pageSize: number;
+}
+
+@Injectable()
+export class UsersService {
+    private userSequence = 1;
+    private readonly users: UserRecord[] = [];
+
+    constructor(
+        @Optional()
+        @InjectDataSource()
+        readonly dataSource?: DataSource,
+    ) {}
+
+    async upsertTikTokUser(input: UpsertTikTokUserInput) {
+        if (this.hasDatabase()) {
+            const repository = this.dataSource.getRepository(User);
+            const existing = await repository.findOne({
+                where: { tiktokOpenId: input.tiktokOpenId },
+            });
+
+            if (existing) {
+                existing.tiktokUnionId = input.tiktokUnionId ?? existing.tiktokUnionId;
+                existing.nickname = input.nickname ?? existing.nickname;
+                existing.avatarUrl = input.avatarUrl ?? existing.avatarUrl;
+                const saved = await repository.save(existing);
+                return { user: this.toRecord(saved), isNewUser: false };
+            }
+
+            const user = repository.create({
+                tiktokOpenId: input.tiktokOpenId,
+                tiktokUnionId: input.tiktokUnionId,
+                nickname: input.nickname,
+                avatarUrl: input.avatarUrl,
+                status: "active",
+            });
+            const saved = await repository.save(user);
+            return { user: this.toRecord(saved), isNewUser: true };
+        }
+
+        const existing = this.users.find((user) => user.tiktokOpenId === input.tiktokOpenId);
+        const now = new Date().toISOString();
+
+        if (existing) {
+            existing.tiktokUnionId = input.tiktokUnionId ?? existing.tiktokUnionId;
+            existing.nickname = input.nickname ?? existing.nickname;
+            existing.avatarUrl = input.avatarUrl ?? existing.avatarUrl;
+            existing.updatedAt = now;
+            return { user: existing, isNewUser: false };
+        }
+
+        const user: UserRecord = {
+            id: this.userSequence++,
+            tiktokOpenId: input.tiktokOpenId,
+            tiktokUnionId: input.tiktokUnionId,
+            nickname: input.nickname,
+            avatarUrl: input.avatarUrl,
+            status: "active",
+            createdAt: now,
+            updatedAt: now,
+        };
+
+        this.users.push(user);
+        return { user, isNewUser: true };
+    }
+
+    async findById(id: number) {
+        if (this.hasDatabase()) {
+            const user = await this.dataSource.getRepository(User).findOne({
+                where: { id },
+            });
+            return user ? this.toRecord(user) : undefined;
+        }
+
+        return this.users.find((user) => user.id === id);
+    }
+
+    async listUsers(pagination: PaginationInput): Promise<PaginatedResponse<UserRecord>> {
+        if (this.hasDatabase()) {
+            const page = Math.max(pagination.page, 1);
+            const pageSize = Math.min(Math.max(pagination.pageSize, 1), 100);
+            const repository = this.dataSource.getRepository(User);
+            const [records, total] = await repository.findAndCount({
+                order: { id: "DESC" },
+                skip: (page - 1) * pageSize,
+                take: pageSize,
+            });
+
+            return {
+                list: records.map((user) => this.toRecord(user)),
+                pagination: { page, pageSize, total },
+            };
+        }
+
+        return this.paginate([...this.users].reverse(), pagination);
+    }
+
+    async getUserOrThrow(id: number) {
+        const user = await this.findById(id);
+        if (!user) {
+            throw new NotFoundException("User not found");
+        }
+
+        return user;
+    }
+
+    async updateStatus(id: number, status: "active" | "disabled") {
+        if (this.hasDatabase()) {
+            const repository = this.dataSource.getRepository(User);
+            const user = await repository.findOne({ where: { id } });
+            if (!user) {
+                throw new NotFoundException("User not found");
+            }
+
+            user.status = status;
+            return this.toRecord(await repository.save(user));
+        }
+
+        const user = await this.getUserOrThrow(id);
+        user.status = status;
+        user.updatedAt = new Date().toISOString();
+        return user;
+    }
+
+    private hasDatabase(): this is this & { dataSource: DataSource } {
+        return Boolean(this.dataSource?.isInitialized);
+    }
+
+    private toRecord(user: User): UserRecord {
+        return {
+            id: Number(user.id),
+            tiktokOpenId: user.tiktokOpenId,
+            tiktokUnionId: user.tiktokUnionId,
+            nickname: user.nickname,
+            avatarUrl: user.avatarUrl,
+            status: user.status as "active" | "disabled",
+            createdAt: user.createdAt?.toISOString?.() ?? new Date().toISOString(),
+            updatedAt: user.updatedAt?.toISOString?.() ?? new Date().toISOString(),
+        };
+    }
+
+    private paginate<T>(records: T[], input: PaginationInput): PaginatedResponse<T> {
+        const page = Math.max(input.page, 1);
+        const pageSize = Math.min(Math.max(input.pageSize, 1), 100);
+        const start = (page - 1) * pageSize;
+
+        return {
+            list: records.slice(start, start + pageSize),
+            pagination: {
+                page,
+                pageSize,
+                total: records.length,
+            },
+        };
+    }
+}