ci: fix test identity and align MSRV

[ovaso]

Summary

• configure deterministic Git author and committer identities for GitHub Actions
• unblock integration tests that create commits and merges on clean runners
• correct the declared and CI-tested MSRV from Rust 1.85 to Rust 1.88, matching the language features used by the current source
• synchronize the English and Simplified Chinese compatibility docs, user guides, and changelogs

Root causes

The blocked Dependabot PRs exposed two independent baseline failures on main:

1. integration tests inherited no Git identity on GitHub-hosted runners and failed with Committer identity unknown
2. the source uses stabilized let chains, so it cannot compile on the previously declared Rust 1.85 toolchain

Validation

• cargo +1.88.0 test --locked
• cargo fmt -- --check
• cargo test --locked
• cargo test --locked --no-default-features
• cargo clippy --all-targets --all-features -- -D warnings
• cargo build --locked --release

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 15a595bfd5

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

Scope test Git identity to fixture repositories

Because this env block is workflow-wide, every black-box batch-git invocation and its Git children inherit these values. Git documents the author and committer environment variables as overriding repository identity configuration (Git environment variables); consequently, tests that call configure_identity with a repository-specific name actually commit as Batch Git Tests. CI therefore no longer exercises the documented behavior of preserving each repository's identity and could pass an identity-routing regression. Configure identity in the merge and passthrough fixture repositories that require it, or remove these variables from tested product processes.

Useful? React with 👍 / 👎.

[ovaso]

fix