feat: add PyPI and crates.io wrappers

[rafaelperoco]

Closes part of #13.

Adds two language wrappers around the CLI so the obvious-search install path works in Python and Rust ecosystems:

• pip install secretgenerator — pure-Python wrapper at python/. secretgenerator.password(), .passphrase(), .secret(), .api_key(), .pin(), .entropy() return parsed schema-v1 dicts. SecretgeneratorError.code exposes the stable error code (E_ENTROPY_TOO_LOW, etc.) so callers branch on identifiers rather than message strings.
• cargo add secretgenerator — typed Rust crate at rust-crate/. Builder-pattern options structs (PasswordOptions::default().length(24).charset("alphanum-symbols-v1")), Output and CrackTimeEstimate derive serde, Error::cli_code() exposes the stable code.

Why wrappers, not reimplementations: cryptographic primitives stay in the audited binary with SLSA L3 + cosign keyless. The wrappers just parse JSON.

Both ship CI workflows that:

• Install the latest CLI via the composite action (setup-secretgenerator)
• Build + test on ubuntu/macos/windows
• For Rust: cargo fmt --check and cargo clippy -D warnings

10 pytest cases cover schema pinning, error codes, required-classes guarantee, etc. — all green locally. cargo run --example quickstart produces the expected output.