refactor: replace command link interception with :cmd[] directive

Replace the previous mechanism of intercepting specific command-prefixed
anchor tags with a dedicated `:cmd[]` markdown directive.

- Implement `cmdDirective` for `marked-directive` support.
- Update `CommandLinkManager` to listen for clicks on `[data-cmd]` spans
  instead of parsing `href` attributes.
- Add CSS styles for the new `.cmd-link` class.

src/markdown/cmd.ts

@@ -0,0 +1,44 @@
+/**
+ * marked-directive extension: :cmd[command]{label=Display text} inline syntax.
+ *
+ * Renders a clickable span that dispatches the command to the journal stream
+ * when clicked. The CommandLinkManager component handles the actual dispatch.
+ *
+ * Usage in markdown:
+ *   :cmd[roll 1d20+5]{label=Roll initiative}
+ *   :cmd[spark dungeon room-type]{label=Random room}
+ *   :cmd[stat set strength=18]{label=Set strength}
+ *
+ * If no label is provided, the command text itself is shown.
+ */
+
+export const cmdDirective = {
+  level: "inline" as const,
+  marker: ":",
+  renderer(token: any) {
+    // Only handle :cmd[...], not other :directives
+    if (token.meta.name !== "cmd") return false;
+
+    const command = (token.text || "").trim();
+    if (!command) return "";
+
+    const label = (token.attrs?.label as string) || command;
+
+    return `<span class="cmd-link" data-cmd="${escapeAttr(command)}" role="button" tabindex="0">${escapeHtml(label)}</span>`;
+  },
+};
+
+function escapeHtml(s: string): string {
+  return s
+    .replace(/&/g, "&amp;")
+    .replace(/</g, "&lt;")
+    .replace(/>/g, "&gt;");
+}
+
+function escapeAttr(s: string): string {
+  return s
+    .replace(/&/g, "&amp;")
+    .replace(/"/g, "&quot;")
+    .replace(/</g, "&lt;")
+    .replace(/>/g, "&gt;");
+}

src/markdown/index.ts

@@ -7,6 +7,7 @@ import { gfmHeadingId } from "marked-gfm-heading-id";
 import markedColumns from "./columns";
 import markedCodeBlockYamlTag from "./code-block-yaml-tag";
 import { iconDirective, setIconBase } from "./icon";
+import { cmdDirective } from "./cmd";
 
 // 使用 marked-directive 来支持指令语法
 const marked = new Marked()
@@ -27,6 +28,7 @@ const marked = new Marked()
         level: "container",
       },
       iconDirective,
+      cmdDirective,
     ]),
     {
       extensions: [...markedColumns()],