hashavatar 1.1.0

1.1.0 is a minor release for hashavatar focused on dependency,
sanitization, tooling, source layout, and documentation freshness.

Dependency Updates

Replaced direct zeroize usage with the native sanitization crate API.
Added sanitization 1.2.2 with alloc support.
Added sanitization-crypto-interop 1.2.2 so SHA-512 and optional BLAKE3
hashing use the crypto crates' own hasher-state cleanup hooks through the
sanitization sister crate.
Removed direct zeroize dependency usage and the sha2/blake3 zeroize
feature hooks.
Updated the fuzz harness libfuzzer-sys dependency to 0.4.13.
Refreshed Cargo lockfiles with the latest compatible crate versions.

Fixed-size digest and renderer seed copies now use sanitization::Secret.
SHA-512 identity hashing and cache-key hashing now route through the
sanitization-crypto-interop SHA-512 helper.
The crate's direct sha2 dependency is now dev-only; production SHA-512
hashing reaches sha2 through sanitization-crypto-interop.
Removed a redundant SHA-512 digest Secret wrapper now that the interop
helper owns hasher-state cleanup and the caller already guards the returned
digest.
Optional BLAKE3 XOF output now uses the sanitization-crypto-interop fill
helper with a sanitization::Secret output buffer.
Optional XXH3 digest accumulation now uses a sanitization::Secret guard for
the 64-byte accumulator.
Hash-preimage capacity checks now use release-mode assertions, so future
size-accounting drift cannot silently bypass temporary buffer cleanup.
Optional XXH3 chunk capacity and length checks are collapsed into one
release assertion per chunk.
Hash preimage vectors, encoded-output buffers, temporary JPEG RGB buffers,
and owned RGBA buffers are cleared through sanitization volatile clearing
helpers.
Security controls now document the sanitization-crypto-interop cleanup
boundary for SHA-512 and optional BLAKE3.
cargo-deny now denies duplicate crate versions instead of only warning.

Updated pinned GitHub Actions:
- actions/checkout to v7.0.0
- taiki-e/install-action to v2.82.3
Confirmed Swatinem/rust-cache remains current at v2.9.1.

Updated README installation snippets and compatibility wording to 1.1.0.
Updated the changelog for the 1.1.0 release.
Split the former monolithic src/lib.rs into focused source files, including
per-avatar raster and SVG renderer files, without changing the public API.
Clarified that preimage-capacity assertions are active in all builds as an
intentional fail-secure sanitization guard.
Made starry-background seed rotation precedence explicit without changing the
generated visuals.
Hardened internal gradient color interpolation against future oversized
max_position callers.
Added consistent identity() accessors to hashed dog and robot renderer
structs, matching the existing hashed cat renderer.