feat: add commit name-rev support

[Sebastian Thiel (Byron)]

Tasks

This section is for Byron only. Models continuing this PR must not add, remove, check, uncheck, rename, or reorder checkboxes here.

• refackiew

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Everything below this line was generated by Codex GPT-5.

Created by Codex on behalf of Byron. Byron will review before this is ready to merge.

Summary

Implements Git-style commit name lookup for issue #1268.

• Added gix_revision::name_rev() over caller-provided ref tips, so low-level revision logic only knows the prepared names it is allowed to use.
• Added gix::Commit::name_rev() with a configurable platform for ref selection, repeated include/exclude filters, and id fallback formatting.
• Reused the describe ref collection path where it fit, while keeping name-rev display names and filtering behavior separate where Git requires different output.
• Added gix commit name-rev with --tags, repeated --refs <pattern>, repeated --exclude <pattern>, --always, --no-undefined, and --name-only.

Issue

Fixes #1268

The issue asks for functionality similar to:

git name-rev --no-undefined --always 4e2fd00

for shell integration use cases that need to find a branch/ref-based name for a commit.

Git Baseline

Used Git's builtin/name-rev.c behavior as the baseline: prepared ref tips are propagated backwards through the commit graph, first-parent ancestors format as name~N, side-parent paths format as name^M/name~N^M, annotated tags get ^0 when naming their peeled commit, and filtering is handled before the revision-layer walk.

Additional spot checks compared local Git 2.50.1 with the new gix commit name-rev implementation across branch, tag, merge, include, exclude, --tags, --always, and --name-only combinations.

Validation

• cargo fmt
• cargo test -p gix-revision name_rev
• cargo test -p gix commit::name_rev
• cargo test -p gix commit::describe::tags_preserve_the_full_git_timestamp_range
• cargo test -p gitoxide-core commit
• cargo check -p gix -p gitoxide-core
• cargo check -p gix-revision --all-features
• cargo check -p gitoxide
• just clippy -D warnings -A unknown-lints --no-deps
• cargo run -q -p gitoxide --bin gix -- commit name-rev --no-undefined --always --exclude='tags/*' --exclude='remotes/*' HEAD
• GIX_TEST_FIXTURE_HASH=sha256 targeted fixture tests for the new name-rev fixtures
• codex review --commit 29ce60c6729894abeaa230fa7801d259613dd0a1

Attempted cargo check -p gix -p gix-revision -p gitoxide-core --all-features, but it fails before this change is reached because gix-protocol rejects enabling its mutually exclusive blocking-client and async-client features together.