refactor(profiles): drop manual snapshot update now that switching autosaves

Since switching projects automatically saves the current configuration
back to the project being left, the per-project "update from current"
button is redundant and even harmful: it allowed overwriting another
project's snapshot with the current state, breaking the invariant that
a project holds the state you last left it in.

- Remove the resnapshot button and confirm dialog from the manage
  dialog; drop the now-unused scope prop and PROFILE_SCOPE_LABELS
- Add a footer Close button to the manage dialog (overlay click is
  disabled app-wide, so it previously could only be closed via Esc)
- Update manageDescription in all four locales to describe the
  autosave behavior; remove the two dead i18n keys
- Fix a shadowed `warnings` vec in ProfileService::apply that silently
  dropped autosave-failure warnings before they reached the frontend
- Mention auto-capture on next switch in the "no snapshot for this
  scope yet" warning and doc comments

The backend update command keeps its resnapshot parameter; it is now
only exercised by the pre-switch autosave path.

src/components/profiles/ProfileSwitcher.tsx

@@ -246,7 +246,6 @@ export function ProfileSwitcher({ activeApp }: ProfileSwitcherProps) {
 
       <ProfileManageDialog
         isOpen={isManageOpen}
-        scope={scope}
         onClose={() => setIsManageOpen(false)}
       />
     </>