feat(wasi): complete Node 26 parity

[TheHypnoo]

Summary

Completes Node.js 26.5.0 compatibility for node:wasi.

Changes

• Implements WASI construction, lifecycle, import surface, preview1 syscall semantics, and warnings.
• Adds WebAssembly command/reactor bridging and native-module export parity.
• Validates intentional proc_exit(7) through the standard expected-output path.

Related issue

Closes #6771

Test plan

• ./run_parity_tests.sh --suite node-suite --module wasi — 51 PASS, 0 parity failures, 0 compile failures, 0 crashes, 0 node failures, 0 skips
• cargo fmt --check
• cargo test -p perry-runtime wasi --lib
• git diff --check

Checklist

• I have NOT bumped the workspace version or edited CLAUDE.md / CHANGELOG.md
• My commit follows the feat: convention
• I've read CONTRIBUTING.md and agree to the Code of Conduct