The transpiler treated any list with a non-symbol head as a data list,
emitting [head, args] as a JS array literal. When head is a sub-expression
(another call), it should emit (head)(args) — a function call.
This fixes the custom special forms dispatch in transpiled code:
Before: [get(_customSpecialForms, name), args, env] (array — broken)
After: (get(_customSpecialForms, name))(args, env) (call — correct)
Also fixes IIFE patterns: ((fn (x) body) arg) now emits
(function(x) { ... })(arg) instead of [function(x){...}, arg]
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>