refactor: remove knowledge base references from AI agent model and related services

- Removed KnowledgeIDs from CreateAIAgentRequest and AIAgentResponse.
- Updated buildAIAgentResponseWithLocale to eliminate knowledge base name retrieval.
- Refactored AI agent repository and service to remove knowledge base handling.
- Adjusted dashboard service to no longer track AI agents without knowledge bases.
- Modified knowledge base service to check for workflow references instead of AI agent references.
- Updated frontend components to remove knowledge base selection and display.
- Enhanced workflow validation to ensure knowledge retrieve nodes have associated knowledge bases.

internal/pkg/dto/request/ai_request.go

@@ -54,7 +54,6 @@ type CreateAIAgentRequest struct {
 	HandoffMode         enums.AIAgentHandoffMode        `json:"handoffMode"`
 	FallbackMode        enums.AIAgentFallbackMode       `json:"fallbackMode"`
 	FallbackMessage     string                          `json:"fallbackMessage"`
-	KnowledgeIDs        []int64                         `json:"knowledgeIds"`
 	SkillIDs            []int64                         `json:"skillIds"`
 	DirectTools         []AIAgentMCPToolRequest         `json:"directTools"`
 }

internal/pkg/dto/response/ai_response.go

@@ -85,8 +85,6 @@ type AIAgentResponse struct {
 	FallbackMode        enums.AIAgentFallbackMode       `json:"fallbackMode"`
 	FallbackModeName    string                          `json:"fallbackModeName"`
 	FallbackMessage     string                          `json:"fallbackMessage"`
-	KnowledgeIDs        []int64                         `json:"knowledgeIds"`
-	KnowledgeBaseNames  []string                        `json:"knowledgeBaseNames"`
 	SkillIDs            []int64                         `json:"skillIds"`
 	Skills              []AIAgentSkillResponse          `json:"skills"`
 	DirectTools         []AIAgentMCPToolResponse        `json:"directTools"`