fix(memory): fix LLMClient parameter mismatch and add nil logger check

- Update LLMClient test to match NewLLMClient signature by passing nil logger
- Add nil check for logger in NewLLMClient to prevent panic, defaulting to slog.Default()

internal/memory/llm_client.go

@@ -21,6 +21,9 @@ type LLMClient struct {
 }
 
 func NewLLMClient(log *slog.Logger, baseURL, apiKey, model string, timeout time.Duration) *LLMClient {
+	if log == nil {
+		log = slog.Default()
+	}
 	if baseURL == "" {
 		baseURL = "https://api.openai.com/v1"
 	}

internal/memory/llm_client_test.go

@@ -20,7 +20,7 @@ func TestLLMClientExtract(t *testing.T) {
 	}))
 	defer server.Close()
 
-	client := NewLLMClient(server.URL, "test-key", "gpt-4.1-nano-2025-04-14", 0)
+	client := NewLLMClient(nil, server.URL, "test-key", "gpt-4.1-nano-2025-04-14", 0)
 	resp, err := client.Extract(context.Background(), ExtractRequest{
 		Messages: []Message{{Role: "user", Content: "hi"}},
 	})