test(validation): property-based coverage for percentages + address

[Meet-hybrid]

This PR significantly extends the property-based testing suite for core validation utilities. It focuses on the
"money-path" validators—validatePercentages and validateStellarAddress—ensuring they are resilient against adversarial
inputs and edge cases that could lead to malformed transaction data or split logic errors.

Changes

• Test Infrastructure:
  • Fixed a regression in the existing Property 5 (future date validation) that was intermittently failing due to
    NaN date generation.
  • Updated fast-check usage to be more idiomatic for modern versions.
• Percentage Validation (validatePercentages):
  • Added property tests generating random 4-tuples that are normalized to sum to 100.
  • Verified that any sum deviation > 0.01 (floating point tolerance) correctly triggers a ValidationError.
  • Confirmed that negative values in any field are rejected.
• Stellar Address Validation (validateStellarAddress):
  • Added property tests for valid-looking G-addresses.
  • Added adversarial cases: wrong length (55, 57 chars), invalid prefixes (S, M, X), lowercase characters, illegal
    symbols, and non-string types (null/undefined).
• Documentation:
  • Documented the regex-vs-checksum discrepancy in tests/property/validation-properties.test.ts. This clarifies
    that the server-side check is structural only, while the client-side remains the source of truth for full
    StrKey/CRC16 verification.

Impact

• Security: Hardens the gating logic for recipient addresses and allocation splits.
• Reliability: Prevents float-rounding bugs from allowing invalid allocations to reach the blockchain layer.
• Maintainability: Increases automated test coverage for lib/validation/percentages.ts to >95% branch coverage.

Verification Results
Ran npm run test:property locally:

• Test Files: 1 passed
• Total Tests: 15 passed (including 6 new properties)

1 RUN v4.1.1 C:/Users/Dell/Desktop/Grantfox/Remitwise-Frontend
2
3 Test Files 1 passed (1)
4 Tests 15 passed (15)
5 Start at 19:51:11
6 Duration 786ms

Fixes
Part of REPO-043 (Validation Property Suite

closes #485