[yorkie]

Summary

• Add portable full-nostd and Zephyr feature sets
• Support Zephyr-generated headers and toolchain configuration
• Replace std-only synchronization and drop queues with alloc-compatible implementations
• Add runtime configuration for blocking Atomics operations
• Add a Zephyr QEMU example covering threads, promises, SharedArrayBuffer, and Atomics
• Validate no_std feature sets in CI

Testing

• Added runtime coverage for enabling Atomics.wait
• Zephyr example validated on the mps2/an385 QEMU board
• CI now checks minimal and full-nostd configurations

[Copilot]

🟡 Changes recommended

Mut::try_lock currently blocks under parallel + std, which can defeat non-blocking drop paths and risks deadlocks.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR extends rquickjs with portable no_std + alloc support and adds a Zephyr integration path (including header/toolchain handling), plus an embedded Zephyr/QEMU example and CI checks to validate no_std feature sets.

Changes:

• Introduces full-nostd and zephyr feature sets across the workspace (and adjusts dependency feature flags for no_std compatibility).
• Updates runtime/context internals for no_std + parallel (spin-based locking, alloc-compatible drop queue) and adds runtime configuration to allow blocking Atomics operations (Atomics.wait).
• Adds a Zephyr example project and CI checks for minimal + full-nostd builds.

File summaries

File	Description
sys/Cargo.toml	Adds zephyr feature to enable bindgen-based Zephyr builds.
sys/build.rs	Adds Zephyr-specific include/define/toolchain wiring and generated header handling.
README.md	Documents no_std/Zephyr usage and updates supported platform matrix.
examples/zephyr/src/lib.rs	New no_std Zephyr example exercising threads, promises, SAB, Atomics.
examples/zephyr/README.md	Adds Zephyr build/run instructions for the example.
examples/zephyr/prj.conf	Zephyr Kconfig settings for Rust + memory/threading needs.
examples/zephyr/CMakeLists.txt	Minimal Zephyr CMake project using rust_cargo_application().
examples/zephyr/Cargo.toml	Staticlib crate for the Zephyr Rust application.
examples/zephyr/app.overlay	Device-tree overlay tweaks for the selected QEMU board.
core/src/value/convert/from.rs	Gates chrono::Local conversions behind std.
core/src/safe_ref.rs	Switches parallel locking to std Mutex vs spin Mutex based on std.
core/src/runtime/raw.rs	Adds raw runtime set_can_block hook for blocking Atomics.
core/src/runtime/base.rs	Adds safe wrapper Runtime::set_can_block + test coverage.
core/src/runtime/async.rs	Replaces std mpsc drop queue with alloc-compatible shared queue; adds async set_can_block.
core/src/runtime.rs	Re-exports async drop pointer type for parallel futures builds.
core/src/context/owner.rs	Wraps raw context pointer to safely mark it Send/Sync under parallel.
core/src/context/async.rs	Switches async context drop deferral from channel to shared queue.
core/Cargo.toml	Adjusts dependencies/features for no_std, adds full-nostd + zephyr, introduces spin.
Cargo.toml	Adds top-level full-nostd + zephyr features and excludes Zephyr example from workspace.
.github/workflows/ci.yml	Adds CI cargo check coverage for minimal and full-nostd configurations.

Review details

• Files reviewed: 21/21 changed files
• Comments generated: 3
• Review effort level: Lite

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