fix sidebar order and ptyc status bar warning

Revert priority sort in tabsFor() — registration order in
main.dart is the intended sidebar order, not priority. The
priority fields on extensions were dead code.

Remove ptyc from toolchain missing list since NativePty
replaced it.

Co-Authored-By: Claude <noreply@anthropic.com>

lib/kernel/src/toolchain.dart

@@ -54,7 +54,6 @@ class Toolchain extends ChangeNotifier {
         if (_git == null) 'git',
         if (_pql == null) 'pql',
         if (_tmux == null) 'tmux',
-        if (_ptyc == null) 'ptyc',
       ];
 
   /// Returns a Future that completes when resolution finishes.