feat(markdown): support yaml role=tag info string

Accept yaml role=tag alongside legacy yaml/tag so the block
body gets yaml syntax highlighting, matching the CLI role=
attribute convention. Copy button now emits the role=tag form.

src/markdown/code-block-yaml-tag.test.ts

@@ -28,10 +28,7 @@ describe("code-block-yaml-tag", () => {
         "  size: 63x88",
         "  layers:",
         "    - prop: title",
-        "      x1: 1",
-        "      y1: 1",
-        "      x2: 5",
-        "      y2: 1",
+        "      pos: 1,1-5,1",
         "      font: 12",
         "```",
       ].join("\n"),
@@ -47,12 +44,38 @@ describe("code-block-yaml-tag", () => {
     expect(config.layers).toHaveLength(1);
     expect(config.layers[0]).toMatchObject({
       prop: "title",
-      x1: 1,
-      y1: 1,
+      pos: "1,1-5,1",
       font: 12,
     });
   });
 
+  test("supports yaml role=tag info string (highlight-friendly)", () => {
+    const html = render(
+      [
+        "```yaml role=tag",
+        "tag: md-deck",
+        "body: ./cards.csv",
+        "data-config:",
+        "  grid: 5x5",
+        "  layers:",
+        "    - template: |",
+        "        **{{name}}**",
+        "      pos: 1,1-5,8",
+        "```",
+      ].join("\n"),
+    );
+    expect(html).toContain("<md-deck data-config=");
+    expect(html).toContain("./cards.csv</md-deck>");
+    const m = html.match(/data-config="([^"]*)"/);
+    const config = JSON.parse((m![1] || "").replace(/&quot;/g, '"'));
+    expect(config.layers[0].template).toBe("**{{name}}**\n");
+  });
+
+  test("does not swallow plain yaml code blocks", () => {
+    const token = ext.tokenizer("```yaml\nsize: 54x86\n```");
+    expect(token).toBeUndefined();
+  });
+
   test("handles missing tag and body", () => {
     const html = render("```yaml/tag\nclass: foo\n```");
     expect(html).toContain("<tag-unknown class=\"foo\"></tag-unknown>");

src/markdown/code-block-yaml-tag.ts

@@ -8,10 +8,15 @@ export default function markedCodeBlockYamlTag(): MarkedExtension {
         name: "code-block-yaml-tag",
         level: "block",
         start(src: string) {
-          return src.match(/^```yaml\/tag\s*\n/m)?.index;
+          return (
+            src.match(/^```yaml\/tag\s*\n/m)?.index ??
+            src.match(/^```yaml\s+role=tag(?:\s|\n)/m)?.index
+          );
         },
         tokenizer(src: string) {
-          const rule = /^```yaml\/tag\s*\n([\s\S]*?)\n```/;
+          // Both `yaml/tag` (legacy) and `yaml role=tag` (highlight-friendly)
+          // info strings identify a yaml-defined tag block.
+          const rule = /^```yaml(?:\/tag|\s+role=tag[^\n]*)\n([\s\S]*?)\n```/;
           const match = rule.exec(src);
           if (match) {
             const yamlContent = match[1]?.trim() || "";