feat(ci): build and ship Windows x64 prebuilds

[szegedi]

What

Adds win32-x64 to the action-prebuildify only: filter on both build.yml and release.yml, plus the two supporting fixes needed for the Windows artifact pipeline:

• scripts/copy-artifacts.js preserves .exe on Windows when copying Rust [[bin]] outputs (e.g. crashtracker-receiver). Without this, the file gets copied without extension and can't be CreateProcess'd.
• load.js appends .exe on Windows when looking up binaries (both in build/Release and in prebuilds/win32-x64), so libdatadog.find('crashtracker-receiver', true) resolves to the right file.

Why

dd-trace-js's crashtracker is currently a silent no-op on Windows because @datadog/libdatadog ships no Windows prebuild, so libdatadog.load('crashtracker') throws and the wrapper falls back to the noop crashtracker. As a result, repeated Windows-only STATUS_STACK_BUFFER_OVERRUN (0xC0000409) crashes in the dd-trace-js profiler tests produce no crash reports — see PROF-14469.

Upstream libdd-crashtracker (libdatadog v29) already supports Windows: its Cargo.toml has a [target.'cfg(windows)'.dependencies] windows = "0.59.0" block and the default features include collector_windows (in-process collector). Our crates/crashtracker/src/bin/receiver.rs already has a #[cfg(not(unix))] fn main(){} stub.

Test plan

This PR exists primarily to see whether the Windows runner build succeeds. Most likely point of failure is aws-lc-sys (pulled in by rustls with the aws-lc-rs provider). If that breaks on Windows, simplest follow-up is switching the Windows build to the ring provider, or making aws-lc-rs Unix-only.

Related

• PROF-14469 — Windows worker crashes (STATUS_STACK_BUFFER_OVERRUN) on profiler unit-test process exit