ci: enforce consistent code formatting across smartcontract crate

[AbuJulaybeeb]

Summary

• Enforced consistent Rust code formatting across the repository in alignment with CI fmt check requirements.
• Resolved styling and whitespace deviations across 18 smart contract source files in dongle-smartcontract/src/.

Why

Unformatted code accumulates over collaborative development, leading to CI formatting job failures and noisy diffs during code review. Aligning all source files with the standard rustfmt toolchain rules ensures the fmt CI check succeeds cleanly on all PRs.

Implementation

• Applied standard cargo fmt --all to resolve indentation, parameter wrapping, blank lines, and struct/enum field formatting across dongle-smartcontract/src/.
• Preserved all contracts, logic, and test behaviors without functional modifications.

Testing

• cargo fmt --all -- --check
• cargo clippy -p dongle-contract --target wasm32-unknown-unknown -- -D warnings
• cargo test -p dongle-contract (522 passed, 0 failed)
• cargo build -p dongle-contract --target wasm32-unknown-unknown --release
• python3 scripts/validate_deployments.py

Scope / Risk

• Scope: Code style and formatting only in dongle-smartcontract/src/.
• Risk: Low / None (zero business logic or interface changes; all 522 unit and integration tests passing).

Issue

closes #512