fix(client_test): unskip vision test with embedded test image

- Remove t.Skip for TestSendMessageWithImage (qwen3-8b-vision works with base64)
- Add test_image.jpg (400x300) to test directory alongside test file
- Load image at runtime, convert to base64 data URL for API
- Collect full response in bytes.Buffer and verify non-empty output

backend/internal/client/client_test.go

@@ -3,7 +3,9 @@ package client
 import (
 	"bytes"
 	"context"
+	"encoding/base64"
 	"net/url"
+	"os"
 	"testing"
 	"time"
 
@@ -94,11 +96,6 @@ func TestSummarizeChat(t *testing.T) {
 }
 
 func TestSendMessageWithImage(t *testing.T) {
-	// Skip: qwen3-8b-vision on LlamaSwap returns 502 for vision requests.
-	// Run manually when a stable vision backend is available:
-	//   go test -run TestSendMessageWithImage ./internal/client/
-	t.Skip("requires stable vision backend - LlamaSwap qwen3-8b-vision returns 502 for image inputs")
-
 	// Initialize Client
 	baseURL, err := url.Parse("https://llm-api.va.reichard.io/v1")
 	if err != nil {
@@ -110,21 +107,34 @@ func TestSendMessageWithImage(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 120*time.Second)
 	defer cancel()
 
-	// Build Data URL from embedded test image (10x10 red PNG)
-	const dataURL = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAoAAAAKCAYAAACNMs+9AAAADklEQVR42mNk+P/k/wEAn6gE9QxN+7QAAAAASUVORK5CYII="
+	// Load Test Image and Convert to Base64 Data URL
+	imgData, err := os.ReadFile("test_image.jpg")
+	if err != nil {
+		t.Fatalf("Failed to read test image: %v", err)
+	}
+	dataURL := "data:image/jpeg;base64," + base64.StdEncoding.EncodeToString(imgData)
 
 	// Generate Text Stream
+	var outputBuf bytes.Buffer
 	_, err = client.SendMessage(ctx, []*store.Message{{
 		Role:    "user",
-		Content: "What is in this image?",
+		Content: "Describe this image in detail.",
 		Images:  []string{dataURL},
 	}}, model, func(mc *MessageChunk) error {
 		if mc.Message != nil {
-			t.Logf("Received: %s", *mc.Message)
+			outputBuf.WriteString(*mc.Message)
 		}
 		return nil
 	})
 	if err != nil {
 		t.Fatalf("Failed to generate text stream: %v", err)
 	}
+
+	// Verify Response
+	output := outputBuf.String()
+	if output == "" {
+		t.Error("No content was written to the buffer")
+	} else {
+		t.Logf("Model response (%d chars): %s", len(output), output)
+	}
 }