A stack of <jig-accordion-panel> children inside an <jig-accordion>, each
with a clickable header that expands or collapses its own content region. Use it
to group long or optional content into collapsible sections that keep a page
scannable, and bind the two-way expandedPanels model when you need to control
or observe which panels are open.
By default the accordion is single-expand: opening one panel collapses the
others. Each header is a button carrying aria-expanded/aria-controls, and its
content region is a role="region" labelled by that header, so screen readers
announce state and can jump to the revealed content. A panel's id comes from its
panelId input (auto-generated if omitted).
Set multiple to allow any number of panels to be open at once; expanding a
panel then leaves the others untouched.
Set lazy on the accordion to defer each panel's content until it is first
expanded, and cache to keep that content in the DOM after the panel closes.
Both act as defaults that an individual <jig-accordion-panel> can override with
its own lazy / cache inputs.
A disabled panel cannot be toggled by the user, but disabling it does not close
it — a panel that is already expanded (or is expanded programmatically via
expandedPanels) stays open.
jig