Function register_all_handler_side 

pub fn register_all_handler_side(lua: &Lua, ctx: &HostContext) -> LuaResult<()>

Register bridge APIs for the handler Isle.

The handler Isle runs Lua handlers forwarded from the main Isle’s bus.on / bus.on_any via bytecode transfer. It therefore needs the dispatcher-side globals (__bus_handlers, __bus_on_any, __bus_dispatch) installed by [bus::install_bus_dispatcher_on_handler_isle], but does not expose the bus.* Lua table — nested bus.on(...) from inside a handler is intentionally unsupported.