新增用户管理/角色管理/菜单管理功能，修复创作流水线研究脚本

- 用户管理：新增编辑弹窗（修改用户名/角色/密码），增加组织/创建时间/最后登录列
- 角色管理：新增 Role 模型 + CRUD API，admin.html 新增角色管理 tab
- 菜单管理：新增 Menu 模型 + CRUD API，导航栏从 API 动态加载菜单项
- 个人中心：右上角下拉菜单（个人信息/修改密码/退出），新增修改密码 API
- 种子数据：initial_data.py 自动创建默认角色（admin/editor）和默认菜单（7项）
- 修复 research.py 缺少 enrich_topic_research 函数导致导入失败
- 修复 db_helper.py 中 generated_at 条件导致重创作不更新时间戳
- admin.html 操作列加宽防止按钮换行，平台配置增加删除按钮
- articles.html 预览弹窗加 lock-scroll=false 防止页面尺寸跳动

platform/backend/app/database.py

@@ -104,6 +104,18 @@ def init_db():
                 ("trend_field_mappings", "field_name", "VARCHAR"),
                 ("trend_field_mappings", "sort_order", "INTEGER DEFAULT 0"),
                 ("trend_field_mappings", "is_active", "BOOLEAN DEFAULT TRUE"),
+                ("roles", "id", "INTEGER PRIMARY KEY"),
+                ("roles", "name", "VARCHAR UNIQUE"),
+                ("roles", "description", "VARCHAR DEFAULT ''"),
+                ("roles", "is_system", "BOOLEAN DEFAULT FALSE"),
+                ("menus", "id", "INTEGER PRIMARY KEY"),
+                ("menus", "parent_id", "INTEGER REFERENCES menus(id)"),
+                ("menus", "name", "VARCHAR"),
+                ("menus", "path", "VARCHAR"),
+                ("menus", "icon", "VARCHAR DEFAULT ''"),
+                ("menus", "sort_order", "INTEGER DEFAULT 0"),
+                ("menus", "roles", "JSON DEFAULT '[]'::json"),
+                ("menus", "is_active", "BOOLEAN DEFAULT TRUE"),
             ]:
                 try:
                     conn.execute(text(f"ALTER TABLE {table} ADD COLUMN IF NOT EXISTS {col} {typ}"))
@@ -112,6 +124,15 @@ def init_db():
                         conn.execute(text(f"ALTER TABLE {table} ADD COLUMN {col} {typ}"))
                     except Exception:
                         pass
+            # Create roles and menus tables if they don't exist
+            for tbl_sql in [
+                "CREATE TABLE IF NOT EXISTS roles (id SERIAL PRIMARY KEY, name VARCHAR UNIQUE NOT NULL, description VARCHAR DEFAULT '', is_system BOOLEAN DEFAULT FALSE, created_at TIMESTAMP WITH TIME ZONE DEFAULT now())",
+                "CREATE TABLE IF NOT EXISTS menus (id SERIAL PRIMARY KEY, parent_id INTEGER REFERENCES menus(id), name VARCHAR NOT NULL, path VARCHAR NOT NULL, icon VARCHAR DEFAULT '', sort_order INTEGER DEFAULT 0, roles JSON DEFAULT '[]'::json, is_active BOOLEAN DEFAULT TRUE, created_at TIMESTAMP WITH TIME ZONE DEFAULT now())",
+            ]:
+                try:
+                    conn.execute(text(tbl_sql))
+                except Exception:
+                    pass
             conn.commit()
     except Exception:
         pass  # SQLite 不支持 IF NOT EXISTS，但 create_all 对 SQLite 够用，这里仅为 PostgreSQL 迁移