Remove alloy-ethers-typecast

[thedavidmeister]

rain.cli consumes alloy-ethers-typecast (a rev-pinned git dependency). Remove it in favour of plain alloy primitives (Provider, TransactionRequest, SolCall::abi_decode_returns, provider.send_transaction(...).get_receipt()), as done in rain.interpreter's parser (rainlang#511).

Done when

• No alloy_ethers_typecast / alloy-ethers-typecast references remain in this repo.

Part of retiring rainlanguage/alloy-ethers-typecast across the org.

[thedavidmeister]

Resolved by #19 (merged 2026-05-30). alloy-ethers-typecast was dropped from the dependency tree when that PR switched rain-metadata from a path-dep to the published crate (commit a64fb64); it is now absent from main (0 refs in Cargo.toml / Cargo.lock / src). #19 did not reference this issue, so it stayed open — closing as completed now.