feat(contract): add fee distribution at settlement

[Drock0]

[SC-025] Add Fee Distribution At Settlement

Description

This PR resolves issue #25 by introducing a production-grade fee distribution logic during the redeem_time_token (settlement) process for the ChronoPayContract.

Closes #25

Changes Introduced

• Enforced a protocol fee mapping FeeRateBps in DataKey to reliably source dynamic rates.
• Addressed robust handling via a typed Error enum (InvalidFeeRate, CalculationOverflow).
• Introduced configuration endpoints set_fee_rate and get_fee_rate bound under 10000 limit constraints (100%).
• Implemented SettlementResult exposing clear tracking indices returning split bounds: professional_amount and protocol_fee.
• Restructured redeem_time_token returning SettlementResult.

Testing Output

running 6 tests
test test::test_hello ... ok
test test::test_mint_and_redeem ... ok
test test::test_create_time_slot_auto_increments ... ok
test test::test_fee_distribution_splits ... ok
test test::test_negative_settlement_blocked - should panic ... ok
test test::test_invalid_fee_rate_bounded - should panic ... ok

test result: ok. 6 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.01s

[Drock0]

@thlpkee20-wq please merge

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[Drock0]

@thlpkee20-wq