feat: add site-wide glossary with hover tooltips

Every abbreviation and technical term used in the site's copy (RBAC,
NAPALM, config drift, ...) now links to a new /glossary page and shows
a short definition on hover, wherever it appears in body text. Product
and vendor brand names are deliberately excluded — the glossary stays
a dictionary of vocabulary, not a company directory.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/pages/Features.tsx

@@ -1,4 +1,5 @@
 import { useLang } from '../context/LangContext'
+import { linkify } from '../lib/glossary'
 
 function Section({ title, items }: { title: string; items: string[] }) {
   return (
@@ -10,7 +11,7 @@ function Section({ title, items }: { title: string; items: string[] }) {
         {items.map((item) => (
           <li key={item} className="flex items-start gap-2 text-sm text-slate-400 leading-relaxed">
             <span className="mt-1 h-1.5 w-1.5 shrink-0 rounded-full bg-sky-500" />
-            {item}
+            {linkify(item)}
           </li>
         ))}
       </ul>