Sync CI workflows with embedded-rust-template

[jerrysxie]

Summary

Syncs CI workflows with the latest embedded-rust-template.

Changes

check.yml

• Merged separate \clippy\ and \hack\ jobs into unified \hack-clippy\ job with target matrix (\x86_64-unknown-linux-gnu, \ humbv8m.main-none-eabihf)
• Added stricter clippy lint groups: -D clippy::suspicious -D clippy::correctness -D clippy::perf -D clippy::style\
• Added --locked\ flag to \deny, \ est, and \msrv\ jobs
• Added \cargo clippy --tests\ step to \ est\ job
• Added new \machete\ job to detect unused dependencies in Cargo.toml files

nostd.yml

• Added --locked\ flag to \cargo check\

Unchanged

• \cargo-vet.yml\ — already up to date
• \cargo-vet-pr-comment.yml\ — already up to date
• MSRV kept at \1.90\ (repo-specific, higher than template's \1.85)

[Copilot]

Pull request overview

Synchronizes this repository’s GitHub Actions CI workflows with the latest embedded-rust-template, tightening linting and improving dependency/toolchain determinism.

Changes:

• Consolidates clippy + feature-powerset checks into a single hack-clippy matrix job (toolchain + target).
• Adds --locked to multiple Cargo invocations for more reproducible CI.
• Introduces a machete job to detect unused Cargo dependencies.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
.github/workflows/check.yml	Unifies hack+clippy, tightens clippy lint groups, adds --locked in more jobs, and adds cargo-machete job.
.github/workflows/nostd.yml	Adds --locked to the no-std cargo check invocation.

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[Copilot]

The comment about having “intentionally no target specifier” is now inaccurate since the command includes --target ${{ matrix.target }}. Please update or remove the comment/link so it matches the current invocation.

Suggested change

	# intentionally no target specifier; see https://github.com/jonhoo/rust-ci-conf/pull/4
	# Run clippy over all feature combinations for each target in the matrix.

[Copilot]

In hack-clippy, the action ref is dtolnay/rust-toolchain@stable while the job installs a matrix toolchain (stable/beta). For consistency with the msrv job (which uses @master when toolchain: is variable) and to avoid any ambiguity about what ref is expected to support, consider using the same ref pattern here.