feat: Support multiple knowledge base binding in pipelines (#1766)

* Initial plan

* Add multi-knowledge base support to pipelines

- Created database migration dbm010 to convert knowledge-base field from string to array
- Updated default pipeline config to use knowledge-bases array
- Updated pipeline metadata to use knowledge-base-multi-selector type
- Modified localagent.py to retrieve from multiple knowledge bases and concatenate results
- Added KNOWLEDGE_BASE_MULTI_SELECTOR type to frontend form entities
- Implemented multi-selector UI component with dialog for selecting multiple knowledge bases

Co-authored-by: RockChinQ <45992437+RockChinQ@users.noreply.github.com>

* Add i18n translations for multi-knowledge base selector

Co-authored-by: RockChinQ <45992437+RockChinQ@users.noreply.github.com>

* Fix prettier formatting errors in DynamicFormItemComponent

Co-authored-by: RockChinQ <45992437+RockChinQ@users.noreply.github.com>

* Add accessibility attributes to knowledge base selector checkbox

Co-authored-by: RockChinQ <45992437+RockChinQ@users.noreply.github.com>

* fix: minor fix

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: RockChinQ <45992437+RockChinQ@users.noreply.github.com>
Co-authored-by: Junyan Qin <rockchinq@gmail.com>

templates/default-pipeline-config.json

@@ -45,7 +45,7 @@
                     "content": "You are a helpful assistant."
                 }
             ],
-            "knowledge-base": ""
+            "knowledge-bases": []
         },
         "dify-service-api": {
             "base-url": "https://api.dify.ai/v1",

templates/metadata/pipeline/ai.yaml

@@ -80,16 +80,16 @@ stages:
           zh_Hans: 除非您了解消息结构，否则请只使用 system 单提示词
         type: prompt-editor
         required: true
-      - name: knowledge-base
+      - name: knowledge-bases
         label:
-          en_US: Knowledge Base
+          en_US: Knowledge Bases
           zh_Hans: 知识库
         description:
-          en_US: Configure the knowledge base to use for the agent, if not selected, the agent will directly use the LLM to reply
+          en_US: Configure the knowledge bases to use for the agent, if not selected, the agent will directly use the LLM to reply
           zh_Hans: 配置用于提升回复质量的知识库，若不选择，则直接使用大模型回复
-        type: knowledge-base-selector
+        type: knowledge-base-multi-selector
         required: false
-        default: ''
+        default: []
   - name: tbox-app-api
     label:
       en_US: Tbox App API