initial commit — Neuron landing page

Bubble-style chat UI, return visit memory replay, values section,
favicon, Neuron-generated email bodies, 3-question return flow.

src/main.el

@@ -0,0 +1,7 @@
+// main.el — Neuron landing page server
+
+let html_path: String = cwd() + "/src/landing.html"
+println("Neuron landing · serving " + html_path)
+state_set("__html_file__", html_path)
+
+http_serve(3001)