refactor: integrate heromodels RPC with heroserver

- Integrate heromodels RPC as a handler within heroserver
- Update API endpoint to use standard JSON-RPC format
- Add generated curl examples with copy button to docs
- Improve error handling to return JSON-RPC errors
- Simplify heromodels server example script

lib/schemas/jsonrpc/handler.v

@@ -145,5 +145,8 @@ pub fn (handler Handler) handle(request Request) !Response {
 	}
 
 	// Execute the procedure handler with the request payload
-	return procedure_func(request) or { panic(err) }
+	return procedure_func(request) or {
+		// Return proper JSON-RPC error instead of panicking
+		return new_error(request.id, internal_error)
+	}
 }