fix(app-headless-cms): fix dynamic zone template edit dialog and description overflow

[Pavel910]

Summary

• Fix: clicking Edit on a collapsed Dynamic Zone template accordion item now opens the edit dialog (previously only worked when the accordion was expanded)
• Fix: long template descriptions in the "Insert a template" dialog no longer stretch the layout — list view wraps text, grid view clamps to 2 lines

Changes

• DynamicZone.tsx — lift templateToEdit state here; render TemplateDialog outside the Accordion so it mounts regardless of accordion state
• DynamicZoneTemplate.tsx — replace internal dialog state with onEditTemplate callback to parent; use defaultOpen instead of open so the accordion stays uncontrolled after parent re-renders
• TemplateListItem.tsx — remove truncate from description to allow natural text wrapping in list view
• TemplateGridItem.tsx — add line-clamp-2 to description to keep grid cards uniform

Test plan

• Open content model editor with a Dynamic Zone field containing multiple templates
• Collapse all accordion items, click Edit on any template — dialog should open
• Accordion items expand/collapse normally by clicking the chevron
• Open "Insert a template" dialog in list view — long descriptions wrap to multiple lines
• Switch to grid view — long descriptions are clamped to 2 lines with ellipsis