build(v8): use Python-safe custom build 11.9.9

[syrusakbary]

Summary

Align EdgeJS with V8 custom build 11.9.9, including the Python shared-library TLS fixes and Linux ARM64 compatibility updates.

• Advance napi to 38834f059fea9df3585e2d76d31c255fa13f5dc9, merged via fix(v8): use Python-safe 11.9.9 prebuilts napi#72. This also includes the previously merged prebuilt/C-character portability fixes since EdgeJS's old N-API pin.
• Update the root Makefile's cache version and the Nix development shell's version, download URL, and SHA-256/SRI hash.
• Update the existing V8 build notes and task validation record. No EdgeJS runtime sources change.

The release tag 11.9.9 embeds upstream V8 13.6.233.17; these are distinct version identifiers.

Validation

• Downloaded Linux amd64 and Darwin ARM64 archives match GitHub's release digests; the Nix SRI is computed from the verified Linux archive. Nix itself is not installed locally, so a full Nix shell evaluation is not claimed.
• Native EdgeJS build and runtime/compression smoke pass against the actual 11.9.9 archive and updated N-API pin.
• Standard EdgeJS Node compatibility lane: 1,749/1,749 passed.
• Shipping CLI REPL test: 30/30 direct repetitions passed.
• Full C++ CTest run: 1,441 passed, 18 expected skips, one intermittent REPL multiline-navigation wrapper failure. A controlled comparison using the same compiled test objects and verified old/new V8 archives reproduces it with both releases: old 11.9.2 failed 3/30 repetitions; new 11.9.9 failed 2/30. This is a pre-existing wrapper flake, not a green full-CTest claim. No runtime change or test suppression is included.

Upstream N-API passed all eight CI jobs plus 93 native tests on each of macOS ARM64 and Ubuntu 22.04 ARM64. A shared library linked to the actual ARM64 archive loaded in Python on Ubuntu 22.04 and executed V8 JavaScript. Wasmer's SDK branch consumes this same N-API commit in wasmerio/wasmer#6956; a companion SDK dependency-pin PR follows.

Integrated and validated by Codex, an OpenAI coding agent, at the repository owner's request.