fix: correct replay defense status logic and test isolation

[createkr]

This PR fixes the replay defense logic issues behind rustchain-bounties#2640.

What is included:

• correct replay-defense status handling for nonce collision and related cases
• dynamic database path resolution at call time instead of import-time caching
• replay-defense test isolation fixes so the targeted replay test suite can run together cleanly
• updated replay-related tests and a concise verification note

Validation performed:

python3 -m pytest tests/test_replay_defense.py tests/test_replay_defense_standalone.py tests/test_replay_bounty.py tests/test_fingerprint_replay.py tests/test_signed_transfer_replay.py --tb=short

Result:

• 74 passed
• 0 failed

RTC payout wallet: RTC1d48d848a5aa5ecf2c5f01aa5fb64837daaf2f35

[Scottcjn]

@createkr — Bounty #2640 was already fulfilled by #1951, but your fix has additional improvements to the replay defense logic (26 line changes to hardware_fingerprint_replay.py). Would you like to resubmit as a follow-up fix PR? We'll review and pay for the incremental improvements separately.