Require the caller to prove ownership on deregister by providing the
pubkey that was used during registration. The stored pubkey is loaded
from registry.json and compared byte-for-byte against the supplied key.
Changes:
- Add get_pubkey() helper to lib/ports.sh
- Update do_deregister() to verify caller pubkey before removing project
- Update SSH protocol to "deregister <project> <pubkey>"
- Update bin/disinto CLI to read tunnel keypair and pass pubkey
- Return {"error":"pubkey mismatch"} on failure (no pubkey leakage)
- Add unit tests for both success and failure paths
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
