Aligns tests/unit/database.test.ts with the existing convention in
oauth-login-service/credential-resolver/credential-store tests: set
AGENTCOMPANY_ALLOW_INSECURE_VAULT=true in beforeAll so the in-memory
database test can call saveSecret without a real OS keychain.
Follow-up to aa1afd0 which removed the NODE_ENV=test/VITEST auto-enable.