feat(devbox): auto-init submodule and add upstream:sync script

[levonk]

Summary / 摘要

Add a guarded submodule init to the devbox.json init_hook so the pinned deepseek-harness checkout populates automatically on first devbox shell. Add a pnpm run upstream:sync script as the canonical submodule sync command, reachable with or without devbox. Update AGENTS.md, CONTRIBUTING.md, CONTRIBUTING.en.md, README.md, and README.en.md to reference corepack pnpm run upstream:sync instead of the raw git submodule update --init --recursive command.

The init_hook guard is [ -d deepseek-harness/.git ] || git submodule update --init --recursive — it populates the submodule once on first shell, then skips the git invocation on subsequent shells to keep them cheap. A devbox run sync-submodule script delegates to pnpm run upstream:sync for explicit sync-after-pin-move.

Related Issues / 关联 Issue

Resolves #2

Type / 类型

• Bug fix / 问题修复
• Feature / 新功能
• Documentation / 文档
• Release or packaging / 发布或打包
• Tests only / 仅测试
• Other / 其他

Platforms / 影响平台

• Windows installer / Windows 安装包
• Windows portable ZIP / Windows 便携版 ZIP
• macOS Apple Silicon
• macOS Intel
• macOS Universal package / macOS 通用安装包
• Linux
• Not platform-specific / 与平台无关

Verification / 验证

• corepack pnpm run check:layout — bilingual-docs verification passes (42 records, 84 documents consistent); README.i18n.yaml hashes updated to match new README blobs
• corepack pnpm run typecheck
• corepack pnpm run test
• corepack pnpm run check
• Platform package smoke / 平台打包或启动冒烟
• Manual test / 人工测试 — node scripts/verify-bilingual-docs.mjs passes; node --test scripts/bilingual-docs.test.mjs passes (4/4)

Release Notes / 发布说明

Contributor experience improvement: new devbox.json with auto-init submodule guard, new pnpm run upstream:sync script. No user-visible application changes.

[musichen]

Thanks for the solid contribution, @levonk! I reviewed this at a technical level and everything checks out:

✅ devbox.json — Excellent DX improvement. The guarded init pattern is perfect: ensures submodules populate once on first shell, then stay cheap on subsequent invocations.

✅ upstream:sync abstraction — Clean API design. Wrapping raw git commands in a pnpm script makes this discoverable, maintainable, and sets a pattern for future upstream operations.

✅ Bilingual documentation — All updates consistent. Proper hash tracking in README.i18n.yaml shows you understand the bilingual maintenance contract here.

✅ Zero breaking changes — Backward compatible throughout. Tests pass, verification gates clear.

This is exactly the kind of focused, well-executed first contribution that moves the project forward. Approved and merged.

Looking forward to more collaboration on ACRYL. Welcome aboard!