Restore Approach section + Foundation-free nav; self-host resources CSS

The earlier combined commit was blocked mid-run, so re-apply the homepage
Approach section and the unified nav (Focus/Approach/Resources/Contact/Email).
Move foundation.css into resources/ since the foundation dir was removed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

index.html

@@ -40,7 +40,7 @@
       </a>
       <div class="nav-links">
         <a href="/#focus">Focus</a>
-        <a href="/foundation/">Foundation</a>
+        <a href="/#approach">Approach</a>
         <a href="/resources/">Resources</a>
         <a href="/#contact">Contact</a>
         <a class="nav-pill" href="mailto:contact@houstonlabs.us">Email&nbsp;us</a>
@@ -113,6 +113,30 @@
       </div>
     </section>
 
+    <!-- APPROACH -->
+    <section class="section" id="approach">
+      <div class="section-head reveal">
+        <span class="label">/ How we work</span>
+        <h2>From first principles to the real world</h2>
+      </div>
+      <div class="steps-grid">
+        <div class="step reveal">
+          <span class="step-idx">01</span>
+          <h4>Research</h4>
+          <p>First principles to the frontier questions worth asking.</p>
+        </div>
+        <div class="step reveal">
+          <span class="step-idx">02</span>
+          <h4>Prototype</h4>
+          <p>Building what the technology makes newly possible.</p>
+        </div>
+        <div class="step reveal">
+          <span class="step-idx">03</span>
+          <h4>Ship</h4>
+          <p>Systems engineered to reach the real world.</p>
+        </div>
+      </div>
+    </section>
 
     <!-- CONTACT -->
     <section class="contact" id="contact">