roadmap: replace section headline with 'One foundation, many use cases.'

Italic emphasis on 'many use cases' via the deck's existing <em>
treatment. Eyebrow and the rest of the section are untouched.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

protected/index.html

@@ -3370,8 +3370,7 @@ html {
       <header class="platform-cards-head">
         <p class="platform-eyebrow">Implementation roadmap</p>
         <h2 id="platform-roadmap-head" class="platform-title">
-          Set up the platform once, then deliver value in
-          <em>waves of use cases.</em>
+          One foundation, <em>many use cases.</em>
         </h2>
       </header>