Polish: nav hamburger, pillar alignment, wordmark, hero tightening

- Nav: responsive hamburger at ≤1060px, full mobile menu with close behaviors
- Nav: all section anchors are absolute (/#...) for correct cross-page routing
- Pillars: flex column cards with margin-top:auto on taglines — all three align
- About footer: image wordmark matches main page (was plain text "Neuron")
- Hero: "Six patents" → "Patented"; sub-copy trimmed to one clean sentence
- Environmental/efficiency/inference: remove all "memory graph" mentions, cite 40% token reduction
- Environmental: savings calculator (slider, live annual savings calculation)

src/about.el

@@ -120,8 +120,8 @@ fn about_page() -> String {
   <div class=\"container\">
     <div class=\"footer-inner\">
 
-      <a href=\"/\" class=\"footer-brand\" aria-label=\"Neuron home\">
-        <p class=\"footer-brand-name\">Neuron</p>
+      <a href=\"/\" class=\"footer-brand\" aria-label=\"Neuron home\" style=\"display:flex;flex-direction:column;align-items:center;\">
+        <img src=\"/assets/brand/neuron-wordmark-on-light.png\" srcset=\"/assets/brand/neuron-wordmark-on-light@2x.png 2x\" alt=\"Neuron\" height=\"24\" style=\"display:block;margin-bottom:0.35rem;\">
         <p class=\"footer-brand-tagline\">Built Different.</p>
       </a>