fix(billing): add aria-expanded + touch support to BillingComputeGaugeComponent

[PierreBrisorgueil]

Problem

billing.computeGauge.component.vue (PR #4126) has two accessibility gaps:

1. role="region" with tabindex="0" supports keyboard focus expansion, but aria-expanded is missing. Screen readers are not informed of the expand/collapse state.
2. Expansion relies solely on mouseenter/mouseleave and focus/blur. Touch-only users cannot reveal the "remaining · resets" detail line.

Fix

1. Bind :aria-expanded="isExpanded" on the region element
2. Add @click or @touchstart toggle for the expansion state

Affected file(s)

• src/modules/billing/components/billing.computeGauge.component.vue