feat: 宇之然平台 v2.0 - 完整重构版

核心功能:
- 新增 JWT 认证系统，支持管理员登录/登出
- 前后端合并为单一 FastAPI 应用 (端口 8001)
- 系统概览页：6 个统计卡片，点击跳转筛选
- 选题管理页：批量操作 (刷新/创作/优化)，时间列展示
- 系统日志页：整合日志查看功能
- 用户管理页：管理员可创建/删除用户
- 移动端适配：响应式布局，底部导航栏
- 标题居中显示

技术改进:
- 添加 generated_at 字段支持创作时间记录
- 状态更新时自动同步 updated_at
- 所有 API 路由添加 JWT 认证保护
- 前端 authFetch 封装自动附加 Token
- 升级 FastAPI 0.136, Pydantic 2.13 等依赖

修复:
- 修复 API 500 错误 (数据库列缺失)
- 修复 formatRelativeTime 未定义错误
- 修复登录 Token 存储和自动附加逻辑

platform/backend/app/models.py

@@ -3,6 +3,55 @@ from sqlalchemy.sql import func
 from .database import Base
 from datetime import datetime
 
+
+class AuditLog(Base):
+    __tablename__ = "audit_logs"
+
+    id = Column(Integer, primary_key=True, index=True, autoincrement=True)
+    user_id = Column(Integer, nullable=True, index=True)  # 操作用户ID（未登录/匿名可为空）
+    username = Column(String, nullable=False)  # 操作用户名（冗余存储）
+    action = Column(String, nullable=False, index=True)  # 操作类型: login/logout/create_user/update_user/delete_user/publish/etc.
+    resource_type = Column(String, nullable=True, index=True)  # 资源类型: user/topic/publish_record/etc.
+    resource_id = Column(String, nullable=True)  # 资源ID
+    details = Column(JSON, default=dict, nullable=True)  # 操作详情（变更前后、额外信息等）
+    ip_address = Column(String, nullable=True)  # IP 地址
+    user_agent = Column(String, nullable=True)  # User-Agent
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+
+    def to_dict(self):
+        return {
+            "id": self.id,
+            "user_id": self.user_id,
+            "username": self.username,
+            "action": self.action,
+            "resource_type": self.resource_type,
+            "resource_id": self.resource_id,
+            "details": self.details or {},
+            "ip_address": self.ip_address,
+            "user_agent": self.user_agent,
+            "created_at": self.created_at.isoformat() if self.created_at else None
+        }
+
+
+class User(Base):
+    __tablename__ = "users"
+
+    id = Column(Integer, primary_key=True, index=True, autoincrement=True)
+    username = Column(String, unique=True, nullable=False, index=True)
+    password_hash = Column(String, nullable=False)  # bcrypt 哈希
+    role = Column(String, default="user", nullable=False)  # admin/user
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
+
+    def to_dict(self):
+        return {
+            "id": self.id,
+            "username": self.username,
+            "role": self.role,
+            "created_at": self.created_at.isoformat() if self.created_at else None
+        }
+
+
 class Topic(Base):
     __tablename__ = "topics"
 
@@ -21,11 +70,13 @@ class Topic(Base):
     source_file = Column(String)
     created_at = Column(DateTime(timezone=True), server_default=func.now())
     updated_at = Column(DateTime(timezone=True), onupdate=func.now())
+    generated_at = Column(DateTime(timezone=True), nullable=True)  # 选题创作完成时间
     ready_at = Column(Date)
     published_at = Column(Date)
     compliance_score = Column(Integer)
     platform_urls = Column(JSON, default=dict)  # {"zhihu": "...", "wechat": "...", "xiaohongshu": "..."}
 
+
 class Article(Base):
     __tablename__ = "articles"
 
@@ -37,3 +88,23 @@ class Article(Base):
     created_at = Column(DateTime(timezone=True), server_default=func.now())
     compliance_score = Column(Integer)
     html_content = Column(Text)  # 可缓存HTML内容以便预览
+
+
+class PublishRecord(Base):
+    __tablename__ = "publish_records"
+
+    id = Column(Integer, primary_key=True, index=True)
+    topic_id = Column(String, nullable=False)
+    platform = Column(String, nullable=False)  # 发布平台：zhihu/wechat/xiaohongshu
+    action = Column(String, nullable=False)  # 操作：publish/update/delete/invalid
+    status = Column(String, nullable=False)  # 状态：success/failed/partial/cancelled
+    operator = Column(String, nullable=True)  # 操作人
+    description = Column(Text, nullable=True)  # 发布说明
+    suggestion = Column(Text, nullable=True)  # 建议内容
+    url = Column(String, nullable=True)  # 发布后链接
+    error_msg = Column(Text, nullable=True)  # 错误信息
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
+
+    # 关联查询
+    # 可以添加外键关联到 Topic, 但这里保持简单