fix: render mermaid diagrams in docs site

Load mermaid v11 from CDN and render ```mermaid code blocks client-side.
No build dependency needed — works with existing CI workflow.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ako

docs-site/book.toml

@@ -15,6 +15,7 @@ git-repository-url = "https://github.com/mendixlabs/mxcli"
 edit-url-template = "https://github.com/mendixlabs/mxcli/edit/main/docs-site/src/{path}"
 site-url = "/mxcli/"
 additional-css = ["theme/custom.css"]
+additional-js = ["theme/mermaid-init.js"]
 
 [output.html.search]
 enable = true

docs-site/theme/mermaid-init.js

@@ -0,0 +1,24 @@
+// Render mermaid diagrams in mdbook.
+// mdbook renders ```mermaid blocks as <code class="language-mermaid"> inside <pre>.
+// This script loads mermaid from CDN and converts them to rendered SVG diagrams.
+(function () {
+  var blocks = document.querySelectorAll('code.language-mermaid');
+  if (blocks.length === 0) return;
+
+  var script = document.createElement('script');
+  script.src = 'https://cdn.jsdelivr.net/npm/mermaid@11/dist/mermaid.min.js';
+  script.onload = function () {
+    mermaid.initialize({ startOnLoad: false, theme: 'default' });
+
+    blocks.forEach(function (code, i) {
+      var pre = code.parentElement;
+      var container = document.createElement('div');
+      container.className = 'mermaid';
+      container.textContent = code.textContent;
+      pre.parentElement.replaceChild(container, pre);
+    });
+
+    mermaid.run();
+  };
+  document.head.appendChild(script);
+})();