Added node.nostr-sign RPC that uses the node-level Nostr key (matching
getPublicKey), fixing pubkey mismatch where identity.nostr-sign used a
different key. Updated appLauncher to call node.nostr-sign. Added
nostr_sign_hash() to nostr_discovery.rs. Created test-nip07.sh with
11 automated checks (INSTALL-02).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
