fix: re-enable atomic swap tests (benchmarks, mutation, snapshot, chaos)

[villadel]

Re-enables and fixes compile errors in four disabled test modules for the Atomic Swap contract:

- #819 `benchmarks.rs`: Fixed compile errors and re-enabled module. CPU budget tests cover `initiate_swap`, `accept_swap`, `reveal_key`, `cancel_swap`, and `get_swap`.
- #820 `mutation_tests.rs`: Re-enabled module and populated with real mutation cases covering zero/negative price, duplicate IP, auth checks, batch size limits, and expiry boundaries.
- #821 `snapshot_tests.rs`: Re-enabled module with fixed-input snapshots for `SwapRecord` (Pending/Accepted/Completed), `ProtocolConfig`, swap history, and `ArbitratorCommittee`.
- #822 `upgrade_chaos_tests.rs`: Fixed merge-conflict compile errors (`ContractError` variant names) and added tests for concurrent upgrades and mid-swap upgrade state preservation.

Also updated `.gitignore` with additional unnecessary file patterns (`*.log`, `*.tmp`, `*.pid`).

All commits authored by `villadel <marschkayla@gmail.com>`.

close #819
close #820
close #821
close #822

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