feat(acp/handlers): session/request_permission auto-reject

internal/acp/handlers/handlers.go

@@ -49,6 +49,3 @@ func NewFsHandler() *FsHandler {
 	return &FsHandler{Read: NewFsReadHandler(), Write: NewFsWriteHandler()}
 }
 
-// PermissionHandler is the placeholder for session/request_permission.
-// Fields and methods are added in Task D5.
-type PermissionHandler struct{}