#33064 acpmux: fix the base clippy red in additional_dirs' test (cloned_ref_to_slice_refs)

Summary

clippy (changed cmux-tui packages) is red on feat-cmux-next since https://github.com/manaflow-ai/cmux/pull/32811 (09242cc65c5): its new test in cmux-tui/crates/acpmux/src/hub/additional_dirs.rs writes assert_eq!(got, [a.clone()]), which clippy -D warnings refuses (clippy::cloned_ref_to_slice_refs). Every PR whose changed packages build acpmux inherits that red, for example https://github.com/manaflow-ai/cmux/pull/23071.

Base red: https://github.com/manaflow-ai/cmux/actions/runs/41580822611/job/125734988630 (62c09dc65b) and https://github.com/manaflow-ai/cmux/actions/runs/41572819258/job/125710705429 (09242cc65c5).

The fix compares against std::slice::from_ref(&a): the same assertion, without the clone. Test-only change.

Changelog

none

Observed / Not run

• Observed: cmux-ci run --class isolated --script scripts/ci/cmux-tui-rust-check.sh --os linux --arg clippy at b7fce95e384f6aa413e25cf62423814ddf760a1f, step 5d42d2c9ae3a2ae60983574c: passed (Blacksmith run https://github.com/manaflow-ai/cmuxterm-hq/actions/runs/41582037716).
• Not run: the acpmux test itself (the assertion is unchanged in meaning).

🤖 Generated with Claude Code

---

^{Open in [code]smith · Need help on this PR? Tag @codesmith-bot with what you need.}

---

Summary by cubic

Fixes the clippy::cloned_ref_to_slice_refs warning in the acpmux additional_dirs test, which was making the clippy (changed cmux-tui packages) check red on the base branch and on any PR whose changed packages build acpmux.

The test now asserts against std::slice::from_ref(&a) instead of [a.clone()], which is semantically identical but satisfies clippy -D warnings. Test-only change, no behavior change.