fix(ext/popup): stop Escape from leaking past the generator panel

Two related bugs from the gen-panel rewrite (ac15f06):

1. Escape key was bubbling to view-level keydown handlers in login.ts
   and settings-vault.ts, causing the press that closed the panel to
   also navigate the user away from the form/settings. Fix: call
   e.stopPropagation() in the panel's escHandler before closing.

2. settings-vault.teardown() didn't close any open generator panel,
   leaving the panel's escHandler registered and activePanel state
   stale across view transitions. Fix: call closeGeneratorPanel()
   first in teardown.

Plus a configure-defaults context test for the action-row composition
(no use/cancel buttons in that context).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

extension/src/popup/components/generator-panel.ts

@@ -106,7 +106,10 @@ export function openGeneratorPanel(opts: OpenPanelOpts): void {
   opts.trigger.setAttribute('aria-expanded', 'true');
 
   const escHandler = (e: KeyboardEvent): void => {
-    if (e.key === 'Escape') closeGeneratorPanel();
+    if (e.key === 'Escape') {
+      e.stopPropagation();
+      closeGeneratorPanel();
+    }
   };
   document.addEventListener('keydown', escHandler);