- Ledger accepts kind='grant' (a server-owned balance grant, not a payment).
- OPT_TRIAL_CREDITS=N grants N credits once per tenant (idempotent key
trial:<tenant>) on balance/structure, so reserve -> settle is exercised
before any customer purchase.
- sql/020 extends the kind constraint (re-runnable).
- Tests for the grant helper; full suite 1345 passed.
