Add NIP-05 identifiers: store, publish, GUI modal, CLI helpers

- Store an optional nip05 on each profile; publish it in kind 0 metadata
- set-nip05 CLI (+ validation, lower-casing, clear) and nip05-file helper
  that prints the .well-known/nostr.json document for a domain
- Profiles screen: NIP-05 button, handle shown on cards, Nip05Modal with
  client-side validation and Remove action
- Fix Modal stealing focus from autoFocus inputs one frame after open

frontend/electron/main.ts

@@ -186,6 +186,7 @@ const RENDERER_METHODS: ReadonlySet<string> = new Set([
   'publish_profile_metadata',
   'set_profile_picture',
   'rename_profile',
+  'set_nip05',
   'delete_profile',
   'undo_delete',
   'publish_note',