Local clippy (1.96) flags pre-existing code that an older toolchain accepted;
these lints fire on clean main and block `cargo xtask ci`. All rewrites are
behavior-preserving:
- core/date.rs, numfmt/render.rs, functions/math.rs, functions/stat.rs:
`!x.is_finite() || x < a || x >= b` -> `!(a..b).contains(&x)` (Range::contains
is false for NaN/inf, matching the existing is_finite guard).
- functions/util.rs: `!(A && !B)` -> `!A || B`.
- engine/cmd/file.rs: drop a dead `.filter(|| true)`.
- ui-egui/grid.rs: `find(|| true)` was always the first table (use `.first()`);
`wrap || Justify || (nl && wrap)` -> `wrap || Justify`.
- ui-egui/formula_bar.rs: `tab || (enter && false)` -> `tab`.
- engine/cmd/spelling.rs: split the wasm/non-wasm dictionary init so the
non-wasm `mut` no longer warns under wasm check.
justinjohn0306