fix(mediakit): improve unsplash image download reliability

Increase max background image size from 2MB to 5MB to support higher quality images. Extend download timeout from 15s to 30s and use context-aware HTTP requests. Add detailed error logging for download failures. Improve client-side error messages by displaying server error details and exception messages.

routers/web/repo/setting/mediakit.go

@@ -24,7 +24,7 @@ import (
 
 const tplMediaKit templates.TplName = "repo/settings/media_kit"
 
-const maxBgImageSize = 2 * 1024 * 1024 // 2MB
+const maxBgImageSize = 5 * 1024 * 1024 // 5MB
 
 // MediaKit shows the media kit settings page.
 func MediaKit(ctx *context.Context) {
@@ -276,21 +276,30 @@ func MediaKitUnsplashSelect(ctx *context.Context) {
 	}()
 
 	// Download the regular-size image
-	client := &http.Client{Timeout: 15 * time.Second}
-	resp, err := client.Get(regularURL)
+	client := &http.Client{Timeout: 30 * time.Second}
+	imgReq, err := http.NewRequestWithContext(ctx, http.MethodGet, regularURL, nil)
 	if err != nil {
-		ctx.ServerError("Download Unsplash image", err)
+		log.Error("Unsplash select: failed to create request for %s: %v", regularURL, err)
+		ctx.JSON(http.StatusBadGateway, map[string]string{"error": "Failed to download image"})
+		return
+	}
+	resp, err := client.Do(imgReq)
+	if err != nil {
+		log.Error("Unsplash select: failed to download %s: %v", regularURL, err)
+		ctx.JSON(http.StatusBadGateway, map[string]string{"error": "Failed to download image"})
 		return
 	}
 	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
+		log.Error("Unsplash select: image download returned status %d for %s", resp.StatusCode, regularURL)
 		ctx.JSON(http.StatusBadGateway, map[string]string{"error": "Failed to download image"})
 		return
 	}
 
 	data, err := io.ReadAll(io.LimitReader(resp.Body, maxBgImageSize+1))
 	if err != nil {
+		log.Error("Unsplash select: failed to read image body: %v", err)
 		ctx.ServerError("ReadAll", err)
 		return
 	}

templates/repo/settings/media_kit.tmpl

@@ -217,11 +217,14 @@
 								statusEl.textContent = 'Image saved! Reloading…';
 								window.location.reload();
 							} else {
-								statusEl.textContent = 'Failed to save image. Please try again.';
+								let detail = resp.status + ' ' + resp.statusText;
+								try { const j = await resp.json(); if (j.error) detail = j.error; } catch (_) {}
+								statusEl.textContent = 'Failed to save image: ' + detail;
 								statusEl.style.color = 'var(--color-error)';
 							}
 						} catch (e) {
-							statusEl.textContent = 'Network error. Please try again.';
+							console.error('Unsplash select error:', e);
+							statusEl.textContent = 'Network error: ' + e.message;
 							statusEl.style.color = 'var(--color-error)';
 						} finally {
 							el.style.opacity = '1';