fix: resolve React Native, Rust, and Soroban CI failures

[Clement-coder]

Fixes failing CI checks across all three pipelines:

• React Native: updated mobileapp/package.json dependencies and
  fixed Toast.tsx component
• Rust backend: fixed clippy/fmt issues across middleware,
  services, and tests (rate_limit, disputes, cache, soroban_service, etc.
  )
• Soroban contracts: renamed cargo.toml → Cargo.toml (case fix for
  Linux CI), updated contract logic and tests, added missing test
  snapshots for all contracts

Closes Fracverse#229