refactor(werkbank): extract soft-PLC provisioning + ICS probe into werkbank-exec (WB-04a) (#208)

werkbank-exec/src/error.rs

@@ -0,0 +1,16 @@
+//! Error type for the dynamic-execution logic.
+
+/// Anything that can go wrong provisioning and testing a soft-PLC. The compliance
+/// agent maps this into its own `AgentError` at the call boundary.
+#[derive(thiserror::Error, Debug)]
+pub enum ExecError {
+    /// An HTTP request (to OpenPLC) failed.
+    #[error("HTTP error: {0}")]
+    Http(#[from] reqwest::Error),
+    /// A local IO / process error (e.g. invoking `docker`).
+    #[error("IO error: {0}")]
+    Io(#[from] std::io::Error),
+    /// Any other failure, with a message.
+    #[error("{0}")]
+    Other(String),
+}