HarmonyOS/OpenHarmony tier-2 target: CI cargo-check job + remaining sandbox/clipboard gating

[Hmbown]

Background

HarmonyOS/OpenHarmony support was contributed by @shenjackyuanjie in PR #2634 and harvested to main with credit (cfg-gating for Linux-specific surfaces, rustls/ring switch, scripts/ohos-env.{sh,ps1}, check-ohos-deps.sh, execpolicy/parser_ohos.rs, PTY/nix gating). He verified cargo check --target aarch64-unknown-linux-ohos -p codewhale-tui passes on the stewardship branch.

What's missing to call OHOS a real tier-2 target:

Tasks

• CI job: a cargo check --target aarch64-unknown-linux-ohos job (with the OHOS SDK or a stub toolchain) so the target can't silently regress
• Remaining sandbox gating: audit crates/tui/src/sandbox/ for Linux-isms still reachable on OHOS
• Clipboard gating: confirm clipboard integration degrades gracefully on OHOS
• Document the target's support tier in the README/docs build matrix

Invitation

@shenjackyuanjie — you know this target best; the remaining gating work would be very welcome as small PRs against main (the same layered shape as your original contribution). You're on the contributor allowlist, so the gate won't slow you down.

Related: #2634, #2625

[shenjackyuanjie]

I understand, but my final exam week is next week, so I won't be able to start working until at least June 18th