migrate stage build to native elc; chat restores from localStorage on return

Build pipeline
- build-stage.sh replaces the old in-Dockerfile bootstrap.py path. Host
  pre-compiles src/*.el into dist/main.c via the canonical native elc at
  foundation/el/dist/platform/elc and applies the stub-decl sed before
  docker buildx runs.
- Dockerfile.stage drops bootstrap.py + python3 from the builder stage
  and just runs cc on the host-supplied dist/main.c.
- Pre-rendered HTML shells under /srv/landing/ are now chowned to the
  landing user so the El page-builder's fs_write at startup can rewrite
  them — without that, post-COPY edits never reach the served HTML and
  the served page stays as the stale build-time fallback.

Chat restore
- session.verified + session.verifiedAt persist through localStorage so
  a return visit within 24h skips the Turnstile gate and lands directly
  in the restored conversation.
- restoreOrGreet() is the single source of truth for what shows up in
  the message pane after the gate clears: replays prior messages with
  skipSave, else drops the canned hello once and remembers it.
- applyVerifiedDom() hides the gate / reveals the chat row, called both
  from the verified-on-load path (DOMContentLoaded if loading, else
  immediate) and from the Turnstile callback.
- neuronDemoReset clears verified + verifiedAt so the gate returns next
  open.

Extracted JS assets (src/assets/js/*.js + manifest.json) and the
extract-js.py helper land here too — they match what the new build-stage
flow produces and removes the inline <script> blobs from the served HTML.

src/marketplace.el

@@ -132,45 +132,7 @@ fn marketplace() -> String {
     </div>
   </div>
 
-  <script>
-  (function() {
-    var form = document.getElementById('dev-form');
-    if (!form) return;
-    form.addEventListener('submit', async function(e) {
-      e.preventDefault();
-      var msg = document.getElementById('dev-msg');
-      var btn = form.querySelector('button[type=submit]');
-      btn.disabled = true;
-      btn.textContent = 'Sending...';
-      try {
-        var r = await fetch('/api/developer-interest', {
-          method: 'POST',
-          headers: {'Content-Type': 'application/json'},
-          body: JSON.stringify({
-            name: document.getElementById('dev-name').value,
-            email: document.getElementById('dev-email').value,
-            idea: document.getElementById('dev-idea').value
-          })
-        });
-        msg.style.display = 'block';
-        if (r.ok) {
-          msg.textContent = 'Got it. Will review it personally and reach out.';
-          msg.style.color = 'var(--navy)';
-          form.reset();
-        } else {
-          msg.textContent = 'Something went wrong. Email developers@neurontechnologies.ai directly.';
-          msg.style.color = '#c44';
-        }
-      } catch(err) {
-        msg.style.display = 'block';
-        msg.textContent = 'Connection error. Email developers@neurontechnologies.ai directly.';
-        msg.style.color = '#c44';
-      }
-      btn.disabled = false;
-      btn.textContent = 'Send interest →';
-    });
-  })();
-  </script>
+  <script src=\"/assets/js/ce12d682c9e6.js\" defer></script>
 
 </section>