ZswapLocalState

Kotlin wrapper for Midnight's ZswapLocalState (shielded coin tracking).

Manages shielded coin state via Rust FFI. Mirrors DustLocalState pattern.

Lifecycle:

• Create: create or deserialize

• Use: replayEvents, getBalances, getCoinCount

• Persist: serialize / deserialize

• Clean up: close (ALWAYS call when done)

Thread Safety: NOT thread-safe. Use one instance per coroutine scope.