runtime: preserve typed workdir errors

crates/worker-runtime/src/error.rs

@@ -1,5 +1,6 @@
 use crate::execution::WorkerExecutionResult;
 use crate::identity::WorkerId;
+use crate::working_directory::WorkingDirectoryDiagnostic;
 use std::path::PathBuf;
 
 /// Errors returned by the embedded Runtime API.
@@ -38,6 +39,9 @@ pub enum RuntimeError {
     #[error("invalid request: {0}")]
     InvalidRequest(String),
 
+    #[error(transparent)]
+    WorkingDirectory(#[from] WorkingDirectoryDiagnostic),
+
     #[error("config bundle `{bundle_id}` was not found")]
     ConfigBundleMissing { bundle_id: String },