Feature/contract fixes 1026 1027 1028 1029

[Saboleee]

Summary

This PR addresses four critical contract issues: integer overflow handling, deprecated API removal, contract versioning, and testnet deployment verification.

Changes

#1026 — Fix integer overflow in FeeStructure::total()

• Changed total() return type from Option<i128> to Result<i128, PaymentError>
• Prevents silent overflow wrapping in release mode
• Updated all callers and tests to handle Result

#1027 — Update deprecated env.events().publish() API

• Removed deprecated single-argument tuple format from requests contract
• Added #![deny(deprecated)] to all 10 lifebank-soroban contracts
• Prevents future deprecation regressions

#1028 — Add contract versioning

• Added const CONTRACT_VERSION: u32 = 1; to all contracts
• Added pub fn version(env: Env) -> u32 accessor to all contracts
• Backend can now detect stale clients on startup

#1029 — Add testnet deployment with smoke tests

• GitHub Actions workflow now deploys to testnet on both PR and main push
• Added smoke test step that calls version() on each deployed contract
• Verifies returned value matches expected (1)
• Smoke tests required to pass before PR merge

Notes

• Code-only delivery: no build/test/script execution during implementation
• Committer: Saboleee
• All commits follow convention: type: description (#issue-number)

Closes #1026, Closes #1027, Closes #1028, Closes #1029