cli: fix prepack and postpack commands CJS compat

Switch the prepack and postpack commands from using a direct
dynamic import() to the execute.loader pattern, which properly
handles CJS double-wrapping of module exports.

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor

.changeset/fix-prepack-postpack-cjs.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Fixed `prepack` and `postpack` commands failing when the dynamic `import()` goes through a CommonJS compatibility layer that doesn't wrap module exports.

packages/cli/src/modules/build/index.ts

@@ -215,20 +215,34 @@ export const buildPlugin = createCliPlugin({
     reg.addCommand({
       path: ['package', 'prepack'],
       description: 'Prepares a package for packaging before publishing',
-      execute: async ({ args, info }) => {
-        cli({ help: info }, undefined, args);
-        const { pre } = await import('./commands/package/pack');
-        await pre();
+      execute: {
+        loader: () =>
+          import('./commands/package/pack').then(m => {
+            const { pre } = (m as any).default ?? m;
+            return {
+              default: async ({ args, info }) => {
+                cli({ help: info }, undefined, args);
+                await pre();
+              },
+            };
+          }),
       },
     });
 
     reg.addCommand({
       path: ['package', 'postpack'],
       description: 'Restores the changes made by the prepack command',
-      execute: async ({ args, info }) => {
-        cli({ help: info }, undefined, args);
-        const { post } = await import('./commands/package/pack');
-        await post();
+      execute: {
+        loader: () =>
+          import('./commands/package/pack').then(m => {
+            const { post } = (m as any).default ?? m;
+            return {
+              default: async ({ args, info }) => {
+                cli({ help: info }, undefined, args);
+                await post();
+              },
+            };
+          }),
       },
     });