fix(markdown): keep hyphenated block attribute keys

The key pattern \w+ could not cross a hyphen, so data-config=foo was parsed as config=foo and the data- prefix was lost. Allow hyphens in keys, matching parseDirectiveAttrs.

src/markdown/block-attrs.ts

@@ -14,10 +14,16 @@ export interface BlockAttrs {
   extra: Record<string, string>;
 }
 
-/** Parse key="value" and key=value pairs from an attribute string. */
+/**
+ * Parse key="value" and key=value pairs from an attribute string.
+ *
+ * Keys may contain hyphens (e.g. `data-config=...`); the key must start with a
+ * letter or underscore so a leading `-` is treated as part of a value, not a
+ * key.
+ */
 export function parseBlockAttrs(info: string): BlockAttrs {
   const attrs: Record<string, string> = {};
-  const re = /(\w+)\s*=\s*("[^"]*"|\S+)/g;
+  const re = /([A-Za-z_][\w-]*)\s*=\s*("[^"]*"|\S+)/g;
   let m: RegExpExecArray | null;
   while ((m = re.exec(info)) !== null) {
     attrs[m[1]] = m[2].replace(/^"|"$/g, "");