Feat: Add CheetahBytes byte semantics

[mxsm]

Implements the CheetahBytes stage.

Scope:

• Adds CheetahBytes behind the bytes feature.
• Keeps byte semantics separate from CheetahString.
• Requires checked or explicit unsafe conversion from bytes to string.
• Implements serde bytes semantics for CheetahBytes only.

Verification completed locally:

• cargo test --features bytes
• cargo test --features "bytes serde"
• cargo test --no-default-features --features "bytes serde"
• final full verification matrix on integration branch

Closes #113.

[coderabbitai]

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 396ce1c8-87ca-4c4a-a7fc-a9c8556b0b63

📥 Commits

Reviewing files that changed from the base of the PR and between 21aa0bf and 623dd3d.

📒 Files selected for processing (22)

• .github/workflows/ci.yaml
• .github/workflows/release.yml
• Cargo.toml
• README.md
• bench-results/README.md
• benches/comprehensive.rs
• benches/layout.rs
• benches/mutation.rs
• benches/pattern.rs
• scripts/bench-all.ps1
• scripts/bench-all.sh
• src/bytes.rs
• src/cheetah_string.rs
• src/lib.rs
• src/search.rs
• src/serde.rs
• src/simd.rs
• tests/basic.rs
• tests/bytes.rs
• tests/layout_snapshot.rs
• tests/mutation.rs
• tests/search.rs

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/pr-008-cheetah-bytes

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[Copilot]

Pull request overview

This PR introduces a dedicated CheetahBytes type (behind the bytes feature) to separate byte-oriented semantics from CheetahString, while also updating substring search to use memchr/memmem and tightening UTF-8 construction paths for CheetahString.

Changes:

• Add CheetahBytes with explicit checked (TryFrom/try_into_string) and unsafe (into_string_unchecked) conversion into CheetahString, plus byte-oriented serde semantics.
• Remove implicit byte-to-string conversions for CheetahString (replace From with TryFrom and add explicit unsafe constructors), and update serde for CheetahString to serialize as a string.
• Introduce memchr-based substring search utilities (find/rfind) and add new tests/benches plus CI artifact capture for layout snapshots.

Reviewed changes

Copilot reviewed 22 out of 22 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
Cargo.toml	Makes bytes optional, adds memchr, bumps crate version, adds benches/dev-dep.
src/lib.rs	Wires in search module, conditionally adds/exports CheetahBytes, exports CheetahFinder.
src/cheetah_string.rs	Removes implicit byte conversions, adds checked/unsafe UTF-8 constructors, updates search + builder/mutation paths.
src/bytes.rs	New CheetahBytes type with conversions and (feature-gated) serde bytes behavior.
src/search.rs	New memchr/memmem-based find_bytes/rfind_bytes and reusable CheetahFinder.
src/serde.rs	Moves CheetahString serde to string-only serialization; updates UTF-8 validation in visitor paths.
src/simd.rs	Marks now-unused SIMD search helpers as dead_code to avoid warnings.
tests/basic.rs	Updates tests to use checked byte conversions and adjusts ARC/Vec buffer reuse expectations.
tests/bytes.rs	Adds CheetahBytes tests for invalid UTF-8 acceptance, checked/unchecked conversions, and serde bytes semantics.
tests/search.rs	Adds search semantics tests (empty needle, byte indices, unicode alignment, reusable finder).
tests/mutation.rs	Adds mutation/buffer-reuse regression tests for push_str, add, reserve.
tests/layout_snapshot.rs	Adds a layout snapshot test that writes JSON artifacts for CI/benchmarking.
benches/comprehensive.rs	Updates benches to use checked UTF-8 construction.
benches/layout.rs	Adds a bench target that emits layout JSON artifacts.
benches/mutation.rs	Adds mutation-focused criterion benchmarks.
benches/pattern.rs	Adds substring-search-focused criterion benchmarks and finder comparisons.
scripts/bench-all.sh	Adds a convenience runner for tests/benches and capturing outputs.
scripts/bench-all.ps1	Windows equivalent for capturing test/bench outputs.
bench-results/README.md	Documents intended artifact layout for benchmark outputs.
README.md	Updates docs for new version, search behavior, and CheetahBytes feature semantics.
.github/workflows/ci.yaml	Expands CI matrix and uploads layout snapshot artifacts.
.github/workflows/release.yml	Adds a release workflow that validates versions, runs checks/tests, and publishes/releases.

Comments suppressed due to low confidence (1)

src/serde.rs:78

• CheetahStringVisitor implements visit_bytes/visit_byte_buf, but cheetah_string() calls deserializer.deserialize_str(...), which will never dispatch to those byte-oriented visitor methods. If the intent is to accept byte buffers (while validating UTF-8), switch to deserialize_any (or deserialize_bytes/deserialize_byte_buf with appropriate visitor methods); otherwise remove the unused byte visitor methods to avoid misleading behavior.

        fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
        where
            E: Error,
        {
            str::from_utf8(v)
                .map(CheetahString::from_slice)
                .map_err(Error::custom)
        }

        fn visit_borrowed_bytes<E>(self, v: &'a [u8]) -> Result<Self::Value, E>
        where
            E: Error,
        {
            str::from_utf8(v)
                .map(CheetahString::from_slice)
                .map_err(Error::custom)
        }

        fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<Self::Value, E>
        where
            E: Error,
        {
            CheetahString::try_from_vec(v).map_err(Error::custom)
        }
    }
    deserializer.deserialize_str(CheetahStringVisitor)
}

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