Move circuits from anomapay-backend-multichain repo

[XuyangSong]

• Move transfer_witness / _v2, transfer_library / _v2, and transfer_circuit / _v2 from anomapay-backend-multichain
• Bump versions: workspace crates at 2.0.0-rc3; circuit crates bumped to 1.0.0
• Add README.md

Verified: cargo build/test --workspace passes; circuits pass under RISC0_DEV_MODE=1 (transfer_circuit 19, transfer_circuit_v2 13).

Note: ELFs and IDs remain unchanged.

[heueristik]

When running cd transfer_circuit && cargo clippy I get

warning: this expression creates a reference which is immediately dereferenced by the compiler
  --> src/test.rs:58:45
   |
58 |     let encryption_pk = generate_public_key(&encryption_sk.inner());
   |                                             ^^^^^^^^^^^^^^^^^^^^^^ help: change this to: `encryption_sk.inner()`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/rust-1.95.0/index.html#needless_borrow
   = note: `#[warn(clippy::needless_borrow)]` on by default

warning: this expression creates a reference which is immediately dereferenced by the compiler
   --> src/test.rs:426:45
    |
426 |     let encryption_pk = generate_public_key(&encryption_sk.inner());
    |                                             ^^^^^^^^^^^^^^^^^^^^^^ help: change this to: `encryption_sk.inner()`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/rust-1.95.0/index.html#needless_borrow

warning: this expression creates a reference which is immediately dereferenced by the compiler
   --> src/test.rs:548:45
    |
548 |     let encryption_pk = generate_public_key(&encryption_sk.inner());
    |                                             ^^^^^^^^^^^^^^^^^^^^^^ help: change this to: `encryption_sk.inner()`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/rust-1.95.0/index.html#needless_borrow

warning: `token-transfer` (lib) generated 3 warnings (run `cargo clippy --fix --lib -p token-transfer -- ` to apply 3 suggestions)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 30.36s

The same is the case when running cd transfer_circuit_v2 && cargo clippy.

Does this code need to stay as it is so that the verifying keys don't change? If that's the case, ignore my comment.

[heueristik]

Thank you for the work! It looks good to me. There are some outdated paths in the READMEs that we can fix but then we are good to go.