Operating a NIP-98-gated endpoint (register / unregister / quote) needs signed
kind-27235 Authorization headers, and there is no nak on the target hosts. This
example reuses the crate's existing nostr/base64/sha2 deps to mint a
"Nostr <base64-event>" header for curl/CI: generate a throwaway identity or
reuse one via NIP98_SK, sign over the method/path/body, print the header to
stdout. The u-tag is built from FLOONET_BASE_URL to match server verification.
2ro