refactor: change pointer receivers to value types for Conversation and UserMessage in various structs and functions

internal/ai/application/runtime/prepare_service.go

@@ -18,9 +18,6 @@ type prepareService struct {
 }
 
 func (s *prepareService) selectSkill(ctx context.Context, req Request) (*models.SkillDefinition, string, string, error) {
-	if req.UserMessage == nil || req.Conversation == nil {
-		return nil, "", "", nil
-	}
 	result, err := skills.Select(ctx, skills.RuntimeContext{
 		AIAgent:         req.AIAgent,
 		AIConfig:        req.AIConfig,

internal/ai/application/runtime/types.go

@@ -6,8 +6,8 @@ import (
 )
 
 type Request struct {
-	Conversation     *models.Conversation
-	UserMessage      *models.Message
+	Conversation     models.Conversation
+	UserMessage      models.Message
 	AIAgent          models.AIAgent
 	AIConfig         models.AIConfig
 	ManualSkillCode  string
@@ -19,7 +19,7 @@ type Request struct {
 }
 
 type ResumeRequest struct {
-	Conversation *models.Conversation
+	Conversation models.Conversation
 	AIAgent      models.AIAgent
 	AIConfig     models.AIConfig
 	CheckPointID string