[P2] Enlarge the chart-grid delete target for touch input #358

Priority

P2 - a destructive touch control is much smaller than the WCAG 2.2 target-size minimum.

Evidence

At the supported 390x844 viewport, the visible .sq-del control measures about 16.7 by 15 CSS pixels. It is adjacent to other card actions.

Acceptance criteria

• Provide an active area of at least 24 by 24 CSS pixels, or meet the spacing exception.
• Avoid overlap with card selection and information controls.
• Add a touch-profile E2E bounding-box assertion.