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/enterprise.el

@@ -182,65 +182,6 @@ fn enterprise() -> String {
   }
 </style>
 
-<script>
-(function() {
-  var form = document.getElementById('enterprise-form');
-  var submitBtn = document.getElementById('ent-submit');
-  var successDiv = document.getElementById('enterprise-success');
-  var errorDiv = document.getElementById('ent-form-error');
-
-  if (!form) return;
-
-  window.entHeadcountChange = function(val) {
-    document.getElementById('ent-filter-msg-secondary').style.display = val === 'secondary' ? 'block' : 'none';
-    document.getElementById('ent-filter-msg-yes').style.display = val === 'yes' ? 'block' : 'none';
-    submitBtn.disabled = val === 'yes';
-    submitBtn.style.opacity = val === 'yes' ? '0.35' : '1';
-    submitBtn.style.cursor = val === 'yes' ? 'not-allowed' : 'pointer';
-  };
-
-  form.addEventListener('submit', function(e) {
-    e.preventDefault();
-    var headcount = document.getElementById('ent-headcount').value;
-    if (headcount === 'yes') {
-      document.getElementById('ent-filter-msg-yes').style.display = 'block';
-      return;
-    }
-
-    var name = document.getElementById('ent-name').value.trim();
-    var email = document.getElementById('ent-email').value.trim();
-    var company = document.getElementById('ent-company').value.trim();
-    var size = document.getElementById('ent-size').value;
-    var useCase = document.getElementById('ent-use').value.trim();
-
-    if (!name || !email || !company || !size || !useCase || !headcount) {
-      errorDiv.textContent = 'Please fill out all fields.';
-      errorDiv.style.display = 'block';
-      return;
-    }
-
-    errorDiv.style.display = 'none';
-    submitBtn.textContent = 'Sending…';
-    submitBtn.disabled = true;
-
-    fetch('/api/enterprise-inquiry', {
-      method: 'POST',
-      headers: { 'Content-Type': 'application/json' },
-      body: JSON.stringify({ name: name, email: email, company: company, size: size, use_case: useCase, headcount: headcount })
-    })
-    .then(function(r) { return r.json(); })
-    .then(function(data) {
-      form.style.display = 'none';
-      successDiv.style.display = 'block';
-    })
-    .catch(function() {
-      submitBtn.textContent = 'Send inquiry →';
-      submitBtn.disabled = false;
-      errorDiv.textContent = 'Something went wrong. Email enterprise@neurontechnologies.ai directly.';
-      errorDiv.style.display = 'block';
-    });
-  });
-})();
-</script>
+<script src=\"/assets/js/67c990f787eb.js\" defer></script>
 "
 }