[MEDIUM] Circuit has only 2 tests - missing negative test cases

[Junman140]

File: circuits/zk_comply_circuit/src/main.nr, lines 52-76
Severity: MEDIUM

Only test_valid_basic_kyc_ngn and test_valid_enterprise_kes exist. Missing: KYC below threshold (should fail), wrong country (should fail), wrong salt, wrong nullifier, overflow/edge values for u64, zero/max values.