feat(cli): implement device add with signing + deploy key
- Create crates/relicario-cli/src/device.rs: local key storage under
~/.config/relicario/devices/<name>/, current-device tracking, and
git signing config (gpg.format=ssh, user.signingkey, core.sshCommand)
- Add Device command to CLI with add/revoke/list subcommands
- cmd_device add: generates two ed25519 keypairs (signing + deploy),
registers deploy key via Gitea API, stores keys at 0600, configures
git SSH signing, updates .relicario/devices.json and commits
- Gitea config read from flags or RELICARIO_GITEA_{URL,TOKEN,OWNER,REPO}
- --no-gitea flag skips API registration for non-Gitea remotes
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
b1f9f2fbfc