fix: shadow-let soul_url and neuron_origin so the default actually stores

The native elc silently drops bare reassignment inside an if body
(`name = expr` compiles to an orphan expr statement with no store).
Both soul_url and neuron_origin defaulted to empty, breaking every
http_post call to the in-container soul-demo. Switch to let-shadowed
if-expressions until the compiler is fixed.

See: products/web/src/main.el `/api/soul-health` route output.

src/main.el

@@ -1352,10 +1352,8 @@ let html_path: String = src_dir + "/index.html"
 
 // Soul URL — where the demo soul is reachable.
 // Defaults to localhost for local dev; set SOUL_URL for deployed environments.
-let soul_url: String = env("SOUL_URL")
-if str_eq(soul_url, "") {
-    soul_url = "http://localhost:7772"
-}
+let soul_url_env: String = env("SOUL_URL")
+let soul_url: String = if str_eq(soul_url_env, "") { "http://localhost:7772" } else { soul_url_env }
 state_set("__soul_url__", soul_url)
 
 // Stripe config from environment — loaded first so founding count can use it.
@@ -1371,10 +1369,8 @@ let supabase_service_key: String = env("SUPABASE_SERVICE_KEY")
 let supabase_project_url: String = "https://ocojsghaonltunidkzpw.supabase.co"
 
 // Origin — drives Stripe redirect URLs; never hardcoded to localhost.
-let neuron_origin: String = env("NEURON_ORIGIN")
-if str_eq(neuron_origin, "") {
-    neuron_origin = "https://neurontechnologies.ai"
-}
+let neuron_origin_env: String = env("NEURON_ORIGIN")
+let neuron_origin: String = if str_eq(neuron_origin_env, "") { "https://neurontechnologies.ai" } else { neuron_origin_env }
 
 // Founding count — seeded from persist file or live Stripe query.
 let sold_file: String = src_dir + "/founding_sold.txt"