wangjia
40a80467ce
feat(backend): Ed25519 license signing utilities (21A)
- util/license_key.go: LicensePayload struct, GenerateEd25519KeyPair,
IssueLicenseToken (sign), VerifyLicenseToken (verify offline)
- cmd/genkey: one-shot keypair generator with demo sign+verify
- config: add Ed25519PublicKey field (LICENSE_ED25519_PUBLIC_KEY env)
Token format: base64url(header).base64url(payload).base64url(ed25519-sig)
Private key stored in Bitwarden; public key embedded in config/client.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>