- test_usage / test_webhook setUp: get-or-create the cpu_seconds metric and
nexacloud service so the suite no longer collides with existing rows.
- test_invoice_ledger: add _fc_ensure_ca_billing_env (activate CAD + a 13%
sale tax matching _fc_tax_for) so the ledger tests pass on a clean DB.
Canonical test DB: a FRESH db with l10n_ca installed (a prod clone collides
on fixed-code fixtures across 5 test files). Full suite now exits 0.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>