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/en-US.ts

@@ -773,6 +773,23 @@ const enUS = {
     retrieverConfiguration: 'Retriever Configuration',
     retrieverInstallInfo: 'You can install Knowledge Retriever plugins from',
     retrieverMarketLink: 'here',
+    migration: {
+      title: 'Knowledge Base Migration',
+      description:
+        'The new version has refactored the knowledge base into a plugin-based architecture, unifying built-in and external knowledge bases as "Knowledge Engine" plugins. Migration of legacy knowledge base data is required. Your old data has been automatically backed up in the database.',
+      detected:
+        'Found {{total}} knowledge base(s) to migrate ({{internal}} internal, {{external}} external).',
+      startWithInstall: 'Auto-install Plugin & Migrate',
+      startDataOnly: 'Migrate Data Only',
+      dataOnlyHint:
+        '"Migrate Data Only" is for offline/intranet environments. Please install the corresponding plugin manually after migration.',
+      dismiss: 'Discard Original Data',
+      running: 'Migrating knowledge bases, please wait...',
+      success: 'Knowledge base migration completed',
+      error: 'Knowledge base migration failed: ',
+      dismissError: 'Operation failed',
+      retry: 'Retry',
+    },
   },
   register: {
     title: 'Initialize LangBot 👋',