修复后台删不掉内容系统发布的文章，登录状态重启后不再失效

- 删除文章：先删引用它的发布记录和实体关联再删文章（之前顺序反了，数据库外键拒绝删除），并放在一个事务里，失败时不会只删掉一半
- 管理员登录状态存到数据库（admin_sessions，只存令牌哈希），服务重启或部署后不用重新登录；登录过期时后台回到登录页并提示，而不是操作一直失败
- 内容系统发布的文章可修改知识中心列表里的摘要
- 文章缺少扩展记录时，修改分类和发布时间也能保存
- 提示文字改为“约 1 分钟内在网站生效”（前台页面缓存 60 秒）
- 新增不连数据库的单元测试 tests/adminFixes.unit.test.js（其他测试会写 .env 里的库）

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/adminFixes.unit.test.js

@@ -0,0 +1,81 @@
+// Unit tests with the database replaced by a fake: the other suites in this folder write to the database in
+// .env, which is the production one, so these must never touch it.
+const statements = [];
+let rows = {};
+let failOn = null;
+
+const fakeDb = {
+  prepare(sql) {
+    return {
+      run: (...params) => {
+        statements.push(sql);
+        if (failOn && sql.startsWith(failOn)) throw new Error(`fake failure: ${failOn}`);
+        // Like MySQL's foreign keys: content still referenced by a publication cannot be deleted.
+        if (sql.startsWith('DELETE FROM contents') && rows.publication) throw new Error('ER_ROW_IS_REFERENCED_2');
+        if (sql.startsWith('DELETE FROM integration_publications')) rows.publication = null;
+        if (sql.startsWith('INSERT INTO admin_sessions')) rows.session = { token_hash: params[0], user_id: params[1], username: params[2], expires_at: params[3] };
+        if (sql.startsWith('DELETE FROM admin_sessions WHERE token_hash')) rows.session = null;
+        return { changes: 1 };
+      },
+      get: (...params) => {
+        statements.push(sql);
+        if (sql.includes('FROM contents')) return rows.content;
+        if (sql.includes('FROM admin_users')) return rows.user;
+        if (sql.includes('FROM admin_sessions')) return rows.session && rows.session.token_hash === params[0] ? rows.session : undefined;
+        return undefined;
+      },
+      all: () => [],
+    };
+  },
+};
+
+jest.mock('../src/config/database', () => ({ getDb: () => fakeDb, closeDb: () => {}, toMySqlParam: (v) => v }));
+
+const crypto = require('crypto');
+const ContentService = require('../src/services/ContentService');
+const AdminAuthService = require('../src/services/AdminAuthService');
+
+beforeEach(() => {
+  statements.length = 0;
+  failOn = null;
+  rows = { content: { content_id: 'c1', content_type: 'article' }, publication: { content_id: 'c1' } };
+});
+
+test('deleting a content-system article removes what points at it first, in one transaction', () => {
+  ContentService.delete('c1');
+  expect(statements.filter((sql) => !sql.startsWith('SELECT'))).toEqual([
+    'START TRANSACTION',
+    'DELETE FROM integration_publications WHERE content_id = ?',
+    'DELETE FROM entity_content_joins WHERE content_id = ?',
+    'DELETE FROM articles WHERE article_id = ?',
+    'DELETE FROM contents WHERE content_id = ?',
+    'COMMIT',
+  ]);
+});
+
+test('a failed delete is rolled back instead of leaving half an article', () => {
+  failOn = 'DELETE FROM contents';
+  expect(() => ContentService.delete('c1')).toThrow('fake failure');
+  expect(statements[statements.length - 1]).toBe('ROLLBACK');
+  expect(statements).not.toContain('COMMIT');
+});
+
+test('admin logins are kept in the database, so a restart does not log the admin out', () => {
+  const salt = 'ab'.repeat(16);
+  rows.user = { user_id: 'u1', username: 'admin', password_hash: `${salt}:${crypto.scryptSync('secret-pass', salt, 64).toString('hex')}` };
+  const { token } = AdminAuthService.login('admin', 'secret-pass');
+  expect(rows.session.token_hash).not.toBe(token);
+  jest.isolateModules(() => {
+    // A fresh copy of the service stands in for the restarted server.
+    const Restarted = require('../src/services/AdminAuthService');
+    expect(Restarted.verify(token)).toMatchObject({ username: 'admin' });
+    expect(Restarted.verify('wrong-token')).toBeNull();
+  });
+  AdminAuthService.logout(token);
+  expect(AdminAuthService.verify(token)).toBeNull();
+});
+
+test('an expired login is refused', () => {
+  rows.session = { token_hash: crypto.createHash('sha256').update('t').digest('hex'), user_id: 'u1', username: 'admin', expires_at: Date.now() - 1 };
+  expect(AdminAuthService.verify('t')).toBeNull();
+});