Detect pending tab navigations for popup domain suggestions

[Copilot]

Popup domain suggestions previously depended on tabs.onUpdated, so they could lag while a page was still loading. This change tracks main-frame navigation earlier via webNavigation, while falling back to the current document URL if navigation is cancelled.

• Navigation tracking

  • Subscribe to webNavigation main-frame events in TabManager.
  • Update tracked tab URL on navigation start/commit/history/fragment updates.
  • Reload tab data on navigation errors when the pending URL did not commit.

• Extension permissions

  • Add webNavigation permission across supported manifests.

• Test coverage

  • Add focused TabManager tests for:
    • pending main-frame URL updates
    • ignoring sub-frame navigations
    • reverting to current document URL after navigation failure

api.webNavigation.onBeforeNavigate.addListener(TabManager.handleNavigationStarted);
api.webNavigation.onCommitted.addListener(TabManager.handleNavigationCommitted);
api.webNavigation.onErrorOccurred.addListener(TabManager.handleNavigationError);