Touch containment story check fails on sub-pixel rounding

expectContained in src/stories/touch.ts compares bounding rects exactly. Fractional layouts fail on floating-point noise: the EmojiPicker "Touch Grid" story failed with expected 273.4107971 to be ≤ 273.4107857, about 0.00001px. It failed twice on 2026-11-06, on PR #172's CI and on main after #170 merged, and the main failure stopped that commit's image being built.

Fix: allow a 0.01px tolerance. That's far below anything visible, but well above rounding noise, so real overflow still fails.