Refactor AI Agent and AI Config handling across multiple files

- Updated function signatures to accept AI Agent and AI Config as non-pointer types for better clarity and safety.
- Modified instances where AI Agent and AI Config were dereferenced to improve code readability.
- Removed unnecessary nil checks for AI Agent and AI Config, simplifying the logic.
- Adjusted related tests and services to align with the new function signatures.
- Cleaned up code in runtime, skills, and executor packages to ensure consistency in handling AI configurations.

internal/ai/embedding.go

@@ -65,7 +65,7 @@ func (s *embedding) callEmbeddingAPI(ctx context.Context, text string) (*Embeddi
 	if err != nil {
 		return nil, err
 	}
-	client := newOpenAIClient(config)
+	client := newOpenAIClient(*config)
 	embeddingResp, err := client.Embeddings.New(ctx, openai.EmbeddingNewParams{
 		Input: openai.EmbeddingNewParamsInputUnion{
 			OfString: openai.String(text),