http_handler_fn / http_handler4_fn were defined only inside el_runtime.c, so soul
modules (routes/chat/...) that reference them via cross-module forward declarations
couldn't see the types — which broke the Windows link of every module. Moving the
public function-pointer types to the shared header is the correct home and unblocks
the build on all platforms (identical typedef, C11-safe redefinition in el_runtime.c).
With this, the soul links into a native Windows neuron.exe (mingw, static) that boots
and serves HTTP on :7770 — verified /health → 200 {"status":"alive",...} in a Win11 VM.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>