feat: 支持 ONLYOFFICE 持久化配置管理

- 添加 SettingsRenderForm schema 和 renderForm 字段
- 实现数据库 schema 自动迁移（onlyoffice_enabled, onlyoffice_public_url, onlyoffice_jwt_secret_encrypted）
- 新增 resolve_onlyoffice_settings() 函数支持运行时配置解析
- 知识库服务改用数据库配置替代运行时配置
- 前端添加文件渲染配置页面，支持 JWT 密钥管理
- 完善相关测试覆盖

web/tests/knowledge-folder-selection.test.mjs

@@ -0,0 +1,28 @@
+import assert from 'node:assert/strict'
+
+import { resolveInitialKnowledgeFolder } from '../src/views/scripts/knowledgeFolderSelection.js'
+
+function testFallsBackToFirstFolderWhenCurrentFolderDoesNotExist() {
+  const folders = [{ name: '财务知识库' }, { name: '制度政策' }, { name: '差旅规范' }]
+
+  assert.equal(resolveInitialKnowledgeFolder(folders, '差旅规范（旧值）'), '财务知识库')
+}
+
+function testKeepsCurrentFolderWhenItStillExists() {
+  const folders = [{ name: '财务知识库' }, { name: '制度政策' }, { name: '差旅规范' }]
+
+  assert.equal(resolveInitialKnowledgeFolder(folders, '制度政策'), '制度政策')
+}
+
+function testReturnsEmptyStringWhenFoldersAreEmpty() {
+  assert.equal(resolveInitialKnowledgeFolder([], '差旅规范'), '')
+}
+
+function run() {
+  testFallsBackToFirstFolderWhenCurrentFolderDoesNotExist()
+  testKeepsCurrentFolderWhenItStillExists()
+  testReturnsEmptyStringWhenFoldersAreEmpty()
+  console.log('knowledge folder selection tests passed')
+}
+
+run()