Fix 'too many values to unpack' error in corruption checker

- diagnose_image_issue returns tuple (error_type, details), not dict
- Updated to properly unpack the tuple
- Fixed iteration logic to display error info correctly
- Fixes runtime error in Check Corruption tab

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app.py

@@ -272,8 +272,8 @@ def check_image_corruption(image, sensitivity, check_visual):
             check_visual=check_visual
         )
 
-        # Get diagnostic details
-        issues = find_bad_images.diagnose_image_issue(image_path)
+        # Get diagnostic details (returns tuple: error_type, details)
+        error_type, error_details = find_bad_images.diagnose_image_issue(image_path)
 
         # Clean up
         os.unlink(image_path)
@@ -301,9 +301,9 @@ The image passed all validation checks:
 The image has validation problems:
 
 """
-            if issues:
-                for issue_type, issue_desc in issues.items():
-                    result += f"**{issue_type}:**\n{issue_desc}\n\n"
+            if error_type and error_details:
+                result += f"**Issue Type:** {error_type}\n\n"
+                result += f"**Details:** {error_details}\n\n"
             else:
                 result += "❌ Image failed validation but no specific issues identified.\n\n"