dashboard: render markdown file previews in the side panel

clicking a .md / .markdown path reference now opens a marked-rendered
view in the slide-in panel instead of raw text; other files stay raw
in a <pre>. serves the vendored marked bundle at /static/marked.js and
scopes a .md stylesheet to the panel body.

hive-c0re/assets/index.html

@@ -102,6 +102,7 @@
   </div>
 
   <script src="/static/hive-fr0nt.js" defer></script>
+  <script src="/static/marked.js" defer></script>
   <script src="/static/app.js" defer></script>
 </body>
 </html>