fix(installer): narrow error handling in copy() and fix test interdependency

- copy() overwrite:false catch now only ignores ENOENT/ENOTDIR,
  consistent with pathExists(); permission errors propagate correctly
- 'copy creates parent directories' test creates its own fixture
  instead of depending on state from a previous test

test/test-fs-wrapper.js

@@ -270,10 +270,11 @@ async function runTests() {
   });
 
   await asyncTest('copy creates parent directories for dest', async () => {
-    const src = path.join(TMP, 'copy-file-src.txt');
+    const src = path.join(TMP, 'copy-mkdir-src.txt');
+    nativeFs.writeFileSync(src, 'copy mkdir');
     const dest = path.join(TMP, 'copy-deep', 'nested', 'dest.txt');
     await fs.copy(src, dest);
-    assertEqual(nativeFs.readFileSync(dest, 'utf8'), 'copy file', 'copy with mkdir content mismatch');
+    assertEqual(nativeFs.readFileSync(dest, 'utf8'), 'copy mkdir', 'copy with mkdir content mismatch');
   });
 
   await asyncTest('copy copies a directory recursively', async () => {

tools/cli/lib/fs.js

@@ -115,7 +115,10 @@ module.exports.copy = async function copy(src, dest, options = {}) {
       try {
         await fsp.access(dest);
         return; // dest exists, skip
-      } catch {
+      } catch (error) {
+        if (error && error.code !== 'ENOENT' && error.code !== 'ENOTDIR') {
+          throw error;
+        }
         // dest doesn't exist, proceed
       }
     }