feat(install): add interactive install command and module to detect and install missing @git.zone packages

ts/mod_update/index.ts

@@ -5,7 +5,7 @@ import { commitinfo } from '../00_commitinfo_data.js';
 // Curated list of known @git.zone CLI tools to track for updates.
 // This list is intentionally hardcoded to only track official tools.
 // Add new entries here when new @git.zone packages are published.
-const GITZONE_PACKAGES = [
+export const GITZONE_PACKAGES = [
   '@git.zone/cli',
   '@git.zone/tsdoc',
   '@git.zone/tsbuild',
@@ -171,6 +171,24 @@ export const run = async (options: IUpdateOptions = {}): Promise<void> => {
 
   console.log('');
 
+  // Show managed packages that are not installed anywhere
+  const installedNames = new Set(allPackages.map(p => p.name));
+  const notInstalled = GITZONE_PACKAGES.filter(name => !installedNames.has(name));
+
+  if (notInstalled.length > 0) {
+    console.log('Not installed (managed @git.zone packages):\n');
+    console.log('  Package                      Latest');
+    console.log('  ─────────────────────────────────────────');
+    for (const pkgName of notInstalled) {
+      const latest = await pmUtil.getLatestVersion(pkgName);
+      const name = pkgName.padEnd(28);
+      const version = latest || 'unknown';
+      console.log(`  ${name}  ${version}`);
+    }
+    console.log('');
+    console.log('  Run "gtools install" to install missing packages.\n');
+  }
+
   // Filter packages that need updates
   const packagesToUpdate = allPackages.filter(p => p.needsUpdate);