Use isolated pnpm install for nested packages to prevent JSON corruption

Running pnpm install with hoisted mode in nested directories causes
package.json corruption. Use isolated mode (default pnpm behavior without
hoisting flags) for the nested install to avoid conflicts.

Author: jdalton

scripts/install-npm-packages.mjs

@@ -451,10 +451,19 @@ async function installPackage(packageInfo) {
 
         // Explicitly install dependencies in the nested package to ensure test
         // runners (tape, mocha, ava, etc.) are available.
-        await runCommand('pnpm', ['install', ...PNPM_INSTALL_FLAGS], {
-          cwd: installedPath,
-          env: { ...process.env, ...PNPM_INSTALL_ENV },
-        })
+        // Use isolated mode (not hoisted) to avoid conflicts with parent installation.
+        await runCommand(
+          'pnpm',
+          [
+            'install',
+            '--config.confirmModulesPurge=false',
+            '--no-frozen-lockfile',
+          ],
+          {
+            cwd: installedPath,
+            env: { ...process.env, ...PNPM_INSTALL_ENV },
+          },
+        )
 
         // Apply Socket overrides to all nested dependencies recursively.
         await applyNestedSocketOverrides(installedPath)
@@ -739,10 +748,15 @@ async function installPackage(packageInfo) {
 
     // Explicitly install dependencies in the nested package to ensure test
     // runners (tape, mocha, ava, etc.) are available.
-    await runCommand('pnpm', ['install', ...PNPM_INSTALL_FLAGS], {
-      cwd: installedPath,
-      env: { ...process.env, ...PNPM_INSTALL_ENV },
-    })
+    // Use isolated mode (not hoisted) to avoid conflicts with parent installation.
+    await runCommand(
+      'pnpm',
+      ['install', '--config.confirmModulesPurge=false', '--no-frozen-lockfile'],
+      {
+        cwd: installedPath,
+        env: { ...process.env, ...PNPM_INSTALL_ENV },
+      },
+    )
 
     // Apply Socket overrides to all nested dependencies recursively.
     await applyNestedSocketOverrides(installedPath)