Feat/dbm20 rag (#2037)

* feat(rag): add knowledge base migration from v4.9.0 to plugin architecture

Rewrite dbm020 to backup old knowledge_bases data and preserve
external_knowledge_bases table. Add migration API endpoints and
frontend dialog so users can opt-in to auto-install LangRAG plugin
and restore their knowledge bases with original UUIDs preserved.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(rag): query marketplace for actual plugin version instead of 'latest'

The marketplace API does not support 'latest' as a version string.
Fetch the plugin info first to get latest_version, then use that
concrete version for installation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat(rag): add data-only migration option and fix dialog width

Add option to migrate knowledge base data without auto-installing
the LangRAG plugin (for offline/intranet environments). Also
narrow the migration dialog to match other confirmation dialogs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* refactor: to red and no more

* fix lint

* fix ruff lint

* feat: add external migration

* fix: show

* feat: add external plugin auto download

* feat: update migration messages for knowledge base in multiple languages

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Junyan Qin <rockchinq@gmail.com>

web/src/i18n/locales/zh-Hans.ts

@@ -742,6 +742,23 @@ const zhHans = {
     retrieverConfiguration: '检索器配置',
     retrieverInstallInfo: '您可以从',
     retrieverMarketLink: '此处安装知识检索器插件',
+    migration: {
+      title: '知识库迁移',
+      description:
+        '新版本已将知识库重构为插件化架构，并统一内置知识库和外部知识库为「知识引擎」插件，需要对旧知识库数据进行迁移。您的旧数据已自动备份在数据库中。',
+      detected:
+        '共检测到 {{total}} 个知识库需要迁移（{{internal}} 个内置知识库，{{external}} 个外部知识库）。',
+      startWithInstall: '自动安装插件并迁移',
+      startDataOnly: '仅迁移数据',
+      dataOnlyHint:
+        '「仅迁移数据」适合内网环境使用，请在迁移完成后自行安装对应插件',
+      dismiss: '丢弃原数据',
+      running: '正在迁移知识库，请稍候...',
+      success: '知识库迁移完成',
+      error: '知识库迁移失败：',
+      dismissError: '操作失败',
+      retry: '重试',
+    },
   },
   register: {
     title: '初始化 LangBot 👋',