Improve artifact copy diagnostics

Log full src -> dst paths when an artifact is missing or copy fails. This improves triage during packaging without changing behavior or outputs

Author: PeterDaveHello

build.mjs

@@ -445,9 +445,9 @@ async function copyFiles(entryPoints, targetDir) {
             )
             return
           }
-          console.error('Missing build artifact:', entryPoint.src)
+          console.error('Missing build artifact:', `${entryPoint.src} -> ${entryPoint.dst}`)
         } else {
-          console.error('Copy failed:', entryPoint, e)
+          console.error('Copy failed:', `${entryPoint.src} -> ${entryPoint.dst}`, e)
         }
         throw e
       }