Nav, safety, pillars updates

- Nav: all section links are absolute (/#section) - fixes about page back-nav
- Nav: add Environment link
- Safety: "I built" not "we built"; crisis hotline announcement; crisis line coming
- Pillars: rename Learns -> Sharpens with opaque copy that doesn't reveal mechanism

src/pillars.el

@@ -24,9 +24,9 @@ fn pillars() -> String {
 
       <div class=\"pillar-card card-dark reveal\" style=\"transition-delay:150ms\">
         <span class=\"pillar-numeral\" aria-hidden=\"true\">II</span>
-        <h3 class=\"display-md pillar-title\">Learns</h3>
+        <h3 class=\"display-md pillar-title\">Sharpens</h3>
         <div class=\"pillar-rule\"></div>
-        <p class=\"pillar-body\">Gets better at you specifically. Not a generic assistant - yours. The longer you use it, the sharper it becomes. Neuron inference is live day one - a model purpose-built to work with your memory graph, your context, your way of thinking.</p>
+        <p class=\"pillar-body\">The longer you use it, the sharper it gets. Every session builds on the last. Neuron inference is live day one - not a wrapper around someone else&#39;s model. Built for this. Built for you.</p>
         <p class=\"pillar-detail\">Specific to you</p>
       </div>