Add a Switch control next to the relay selector for users to explicitly
enable/disable NIP-70 protected events. Auto-enables when relay
conditions suggest it (no optimal relays), but respects user override.
Includes a help popover explaining protected events with a note that
not all relays support them.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>