feat(core/org): add x25519-dalek dep + stub org module

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TJo44YM3UbBjro2fG6NrKy

crates/relicario-core/src/lib.rs

@@ -93,6 +93,8 @@ pub use import_lastpass::{parse_lastpass_csv, ImportWarning};
 pub mod device;
 pub use device::{fingerprint, DeviceEntry, RevokedEntry, generate_keypair, sign, verify};
 
+pub mod org;
+
 pub mod tar_safe;
 pub use tar_safe::{safe_unpack_git_archive, DEFAULT_MAX_UNCOMPRESSED};