Enhance article import functionality: Add author selection and preserve attribution during imports; update metadata version to 1.1.2.

importer.php

@@ -73,7 +73,7 @@ class BluditGithubImport
                 throw new RuntimeException('Unsupported front matter line: ' . $line);
             }
             $name = $field[1];
-            if (!in_array($name, ['title', 'date', 'slug', 'status', 'tags', 'description', 'category', 'cover'], true) || array_key_exists($name, $meta)) {
+            if (!in_array($name, ['title', 'date', 'slug', 'author', 'status', 'tags', 'description', 'category', 'cover'], true) || array_key_exists($name, $meta)) {
                 throw new RuntimeException('Unknown or duplicate front matter field: ' . $name);
             }
             if ($name === 'tags') {