feat: generate idiomatic Python client bindings

[Rayhab2000]

Summary

Resolves Nanle-code#720.

• Restore binding-language dispatch so generation works for all supported targets.
• Generate typed Python 3.10+ clients with sync and async invocation methods.
• Encode booleans, bytes, dataclasses, and collection arguments deterministically.
• Raise ContractInvocationError with CLI failure details.
• Add keyword-safe identifiers, regression tests, checked-in runtime support, and usage documentation.

Validation

• python -m py_compile client.py
• git diff --check
• cargo test utils::bindings --lib was attempted; crates.io dependency fetching did not complete in the local environment.
• cargo fmt was attempted; rustfmt is not installed for the active toolchain.