feat: add CLI update check with npm registry indicator

On app start, check the npm registry for the latest
@anthropic-ai/claude-code version and compare against the installed
version. If behind, the CLI badge turns amber with a pulsing up-arrow
and a tooltip advising how to update.

Also bumps SUPPORTED_CLI_VERSION to 2.1.72.

src-tauri/src/lib.rs

@@ -134,6 +134,7 @@ pub fn run() {
             list_skills,
             check_for_updates,
             fetch_changelog,
+            check_cli_latest_version,
             save_temp_file,
             register_temp_file,
             get_temp_files,