Attribute Macro handler 

#[handler]

Marks a function as a Galeon handler (filesystem-routed API endpoint).

Registers handler metadata via [inventory] for code generation. The function must be:

• pub (visible to generated router glue)
• Synchronous (not async)
• First parameter is the request type
• Returns Result<R, E>

Additional parameters beyond the first are reserved for future ECS SystemParam injection (#163).

Example

#[galeon_engine::handler]
pub fn dispatch_fleet(cmd: DispatchFleetCmd) -> Result<FleetStatus, FleetError> {
    todo!()
}