- Upgrade CrewInviteDialog with a "Send invite" tab: invite a specific npub
with live invitee preview, optional note, and founder-only "invite as admin"
toggle. Preserves the shareable-link flow on a second tab.
- Add NotificationBell to desktop + mobile headers: unread badge, popover with
incoming crew invites (accept/decline) and pending-confirmation crews
(confirm with public/crew-only visibility).
- Wire useSendCrewInvite / useMyCrewInvites / accept / decline hooks and the
useCrewNotifications aggregator into the UI.
- Membership stays unforgeable (founder p-tag + invitee NIP-32 attestation).
Co-authored-by: shakespeare.diy <assistant@shakespeare.diy>
