Fix JS syntax errors and stage supabase-config CORS in CI

chat-widget.el: apostrophe in El native_js double-quoted strings caused
the El compiler to drop the backslash, producing broken JS single-quoted
strings. Switched those four string literals to double-quoted JS strings
using \" escaping so the compiled output is valid.

main.el: /api/supabase-config was returning 403 for all stage Cloud Run
origins. Added marketing-stage-* prefix to the allowed list so the
checkout page can initialise Supabase during CI E2E runs.

src/main.el

@@ -1172,6 +1172,7 @@ fn handle_request_inner(method: String, path: String, headers: Map, body: String
             || str_eq(req_origin, "https://www.neurontechnologies.ai")
             || str_starts_with(req_origin, "http://localhost:")
             || str_starts_with(req_origin, "http://127.0.0.1:")
+            || str_starts_with(req_origin, "https://marketing-stage-")
         if !origin_ok {
             return "{\"__status__\":403,\"error\":\"forbidden\"}"
         }