feat(debug): debug programs in a plugin run target (#2264)

wit/run-targets.wit

@@ -16,7 +16,10 @@ interface run-targets {
     /// Without workdir-args the wrapper manages its container directory itself.
     /// The wrapper always starts in the configuration's LOCAL working directory.
     /// Environment reaches the wrapper; forwarding into a container depends on its conventions.
-    /// Registration never selects the target. Debugging plugin targets is invalid.
+    /// Registration never selects the target. Debugging requires container-root and an
+    /// explicitly supported language debugger placement. Connect-back adapters listen
+    /// on the host; the target must configure the debuggee to connect to that host.
+    /// Stdio adapters run inside the target and must be installed there.
     record run-target {
         id: string,
         name: string,