GitHub Actions now emits "Node.js 20 actions are deprecated" warnings:
actions are forced to Node.js 24 by default starting 2026-06-16, and
Node.js 20 is removed from the runners on 2026-09-16. Update every
JavaScript action referenced by the workflows and the local composite
actions to the lowest release that runs on Node.js 24:
actions/checkout v4 -> v5
actions/checkout (SHA pin) v4.1.7 -> v5
actions/upload-artifact v4 -> v6 (v5 still Node.js 20)
actions/download-artifact v4 -> v7 (v5/v6 still Node.js 20)
actions/cache[/restore|/save] v4 -> v5
actions/setup-python v5 -> v6
actions/github-script v7 -> v8
docker/setup-buildx-action v3 -> v4
docker/build-push-action v5 -> v7 (v6 still Node.js 20)
docker/login-action v3 -> v4
microsoft/setup-msbuild v2 -> v3
open-watcom/setup-watcom v0 -> v1
Actions already running on Node.js 24 (jwlawson/actions-setup-cmake,
shogo82148/actions-setup-perl, msys2/setup-msys2, dorny/paths-filter)
are left unchanged. These bumps are runtime-only; no workflow uses an
input or output removed by the new majors, and v4-format artifacts
remain compatible across the upload v6 / download v7 backends.
## Summary
- Add non-blocking (incremental) Curve25519 key generation and shared secret via `WC_X25519_NONBLOCK`, modeled after the existing ECC non-blocking pattern (`WC_ECC_NONBLOCK`)
- Implement `curve25519_nb()` and `fe_inv__distinct_nb()` in `fe_low_mem.c` as state-machine variants that return `FP_WOULDBLOCK` to yield after each field multiply
- Add `wc_curve25519_set_nonblock()` API to attach/detach non-blocking context to a key
- Integrate X25519 non-blocking with TLS 1.2/1.3 key share generation and shared secret in `tls.c` and `internal.c` (behind `WC_X25519_NONBLOCK && WOLFSSL_ASYNC_CRYPT_SW`)
- Add `--enable-curve25519=nonblock` configure option (auto-enables `--enable-asynccrypt` and `--enable-asynccrypt-sw`)
- Add X25519 async software dispatch cases in `async.c` and types in `async.h`
- Fix async guard in `curve25519.c` to require `WOLFSSL_ASYNC_CRYPT_SW` (matching other algorithms)
- Overhaul `examples/async/` client/server: non-blocking I/O via `WOLFSSL_USER_IO`, standalone `Makefile`, X25519/ECC mode selection, CI-friendly ready-file sync
- Add `examples/configs/user_settings_curve25519nonblock.h` and CI coverage in `os-check.yml` and new `async-examples.yml` workflow
- Add wolfcrypt test and API test coverage for X25519 non-blocking