Introduces the offline license infrastructure for the Base/Premium editions.
- jsonwebtoken (EdDSA) verifies license JWTs against an embedded Ed25519
public key. The exp claim is mandatory (CWE-613) and is enforced via
Validation::set_required_spec_claims.
- Activation tokens (server-issued, machine-bound) prevent license.key
copying between machines. Storage is wired up; the actual issuance flow
ships with Issue #49.
- get_edition() fails closed to "free" when the license is missing,
invalid, expired, or activated for a different machine.
- New commands/entitlements module centralizes feature → tier mapping so
Issue #48 (and any future gate) reads from a single source of truth.
- machine-uid provides the cross-platform machine identifier; OS reinstall
invalidates the activation token by design.
- Tests cover happy path, expiry, wrong-key signature, malformed JWT,
unknown edition, and machine_id matching for activation tokens.
The embedded PUBLIC_KEY_PEM is the RFC 8410 §10.3 test vector, clearly
labelled as a development placeholder; replacing it with the production
public key is a release-time task.
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