fix: retarget updater to @mosaic/mosaic (#384)

packages/mosaic/src/cli.ts

@@ -12,6 +12,7 @@ import {
   backgroundUpdateCheck,
   checkForUpdate,
   formatUpdateNotice,
+  getInstallCommand,
 } from './runtime/update-checker.js';
 import { runWizard } from './wizard.js';
 import { ClackPrompter } from './prompter/clack-prompter.js';
@@ -354,7 +355,7 @@ program
     try {
       // Relies on @mosaic:registry in ~/.npmrc — do NOT pass --registry
       // globally or non-@mosaic deps will 404 against the Gitea registry.
-      execSync('npm install -g @mosaic/cli@latest', {
+      execSync(getInstallCommand(result), {
         stdio: 'inherit',
         timeout: 60_000,
       });