Toolchain drift: 437 `Array::new(capacity=…)` deprecation warnings across 136 files

[bobzhang]

The current MoonBit nightly deprecates Array::new(capacity=…) in favour of
Array(capacity=…). moon check on a clean main reports 437 warnings, 0
errors across 136 files — verified in a throwaway worktree at main, so
this is toolchain drift and not a regression from any open branch.

scripts/ci/local-gate.sh treats warnings as failures, so the local gate is red
on main until this is swept. CI floats both toolchain channels and passes if
either does (#416), which is why this has not turned CI red.

What this needs. One mechanical sweep PR, following the warning-id campaign
discipline: one warning id per PR, and per-span verification rather than a blind
sed. The deprecation-migration-traps rule applies — the suggested replacement
must be confirmed equivalent for each spelling before it is applied in bulk,
because the two constructors could differ on the zero-capacity or
negative-capacity cases.

Affected areas are broad and untargeted by any current work: xlsx/,
pagelayout/, docx2html/, office/.