perf: do not include scalar children in mark_mt/mark_persistent

[TwoFX]

No description provided.

[TwoFX]

!radar

[leanprover-radar]

Benchmark results for 259f5b0 against ac0f56e are in. No significant results found. @TwoFX

• ✅ build//instructions: -9.7G (-0.09%)

Medium changes (1✅)

• ✅ compiled/iterators//instructions: -3.4M (-0.63%)

Small changes (3✅, 1🟥)

• ✅ compiled/select//instructions: -12.6M (-0.46%)
• ✅ elab/bv_decide_inequality//wall-clock: -58ms (-1.47%)
• 🟥 elab/whnfMatcherImplicitTransparencyCaching//maxrss: +26MiB (+5.27%)
• ✅ lake/inundation/startup//instructions: -3.1M (-1.54%)

[leanprover-bot]

Reference manual CI status:

• ❗ Reference manual CI can not be attempted yet, as the nightly-testing-2026-08-30 tag does not exist there yet. We will retry when you push more commits. If you rebase your branch onto nightly-with-manual, reference manual CI should run now. You can force reference manual CI using the force-manual-ci label. (2026-08-31 10:47:01)

[mathlib-lean-pr-testing]

Mathlib CI status (docs):

• ✅ Mathlib branch lean-pr-testing-14980 has successfully built against this PR. (2026-08-31 11:42:13) View Log