Enh: Contract string representation variants

[mxsm]

Implements the representation contraction stage.

Scope:

• Contracts internal string representation to Inline / Static / Shared / Owned.
• Removes byte-oriented variants from CheetahString core.
• Preserves checked byte construction by converting valid bytes into string-owned storage.
• Confirms all-features layout returns to 32B on the verified x86_64 target.

Verification completed locally:

• cargo test --all-features
• cargo test --no-default-features
• cargo test layout_snapshot --all-features -- --nocapture
• final full verification matrix on integration branch

Closes #112.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 05584eae-6713-4655-b47d-d7129a9f312b

📥 Commits

Reviewing files that changed from the base of the PR and between 21aa0bf and 3eaa760.

📒 Files selected for processing (20)

• .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/cheetah_string.rs
• src/lib.rs
• src/search.rs
• src/serde.rs
• src/simd.rs
• tests/basic.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-007-repr-contraction

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[Copilot]

Pull request overview

Implements the “representation contraction” stage for CheetahString, simplifying the core storage model to string-only variants (Inline / Static / Shared / Owned) while preserving fallible UTF-8 byte-based construction and updating search to use memchr/memmem by default. This aligns with Issue #112’s goal of removing byte-semantics variants from the core representation and making UTF-8 invariants easier to uphold.

Changes:

• Contracted CheetahString internals to string-only variants and shifted checked byte inputs to validated string-owned storage.
• Replaced substring search paths with memchr/memmem (plus a reusable CheetahFinder) and updated docs accordingly.
• Added CI/layout snapshot + new tests/benches/scripts to validate behavior, layout artifacts, and performance-sensitive paths.

Reviewed changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
Cargo.toml	Bumps version to 1.1.0; makes bytes optional; adds memchr; updates feature wiring.
README.md	Updates performance/search messaging and version examples for 1.1.0.
src/lib.rs	Documents memchr-based search; adds search module and re-exports CheetahFinder.
src/cheetah_string.rs	Contracts core representation; replaces byte variants with validated constructors; updates mutation/add/search behavior.
src/search.rs	Adds centralized memchr/memmem byte-search helpers and reusable CheetahFinder.
src/serde.rs	Simplifies serialization via as_str; deserialization validates UTF-8 for byte inputs.
src/simd.rs	Removes SIMD substring search usage from main paths; leaves helpers present but now unused.
tests/basic.rs	Updates conversion tests to new fallible byte constructors and revised buffer reuse expectations.
tests/search.rs	Adds targeted tests for find/rfind/contains semantics and CheetahFinder.
tests/mutation.rs	Adds mutation/builder tests asserting capacity reuse and in-place behavior.
tests/layout_snapshot.rs	Adds a layout snapshot test that emits JSON artifacts and basic layout assertions.
benches/comprehensive.rs	Updates byte-construction benches to use try_from_vec.
benches/layout.rs	Adds a layout artifact emitter for benchmarks.
benches/mutation.rs	Adds mutation-focused benchmarks for push/add/reserve.
benches/pattern.rs	Adds substring search benchmarks including pathological cases and finder reuse.
bench-results/README.md	Documents benchmark artifact layout and capture workflow.
scripts/bench-all.sh	Adds a convenience script to run layout test + benches and collect outputs.
scripts/bench-all.ps1	Adds a PowerShell equivalent for collecting benchmark outputs.
.github/workflows/ci.yaml	Expands CI matrix, adds no_std checks, runs layout snapshot, uploads layout artifacts.
.github/workflows/release.yml	Adds a release workflow with version verification, checks, publish, and GitHub release creation.

Comments suppressed due to low confidence (1)

src/serde.rs:78

• visit_bytes/visit_byte_buf are implemented (and now do UTF-8 validation), but deserialize_str will generally never dispatch to the byte visitors. As a result, formats that encode strings as bytes (or that provide bytes for this field) will still fail to deserialize even when the bytes are valid UTF-8. If the intent is to accept either string or bytes, use deserialize_any (or deserialize_bytes) so the byte visitor paths are reachable.

            CheetahString::try_from_vec(v).map_err(Error::custom)
        }
    }
    deserializer.deserialize_str(CheetahStringVisitor)
}

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