- CategoriesPage: adopt PageShell for header with title and Add Category button
- CategoriesPage: replace return null with skeleton loading state
- CategoriesPage: upgrade dot group headers to left-border accent style
- TemplatePage: mirror PageShell layout (flex-col gap-6) for inline-editable header
- TemplatePage: replace return null with skeleton loading state
- TemplatePage: upgrade dot group headers to left-border accent style
- TemplateName h1: add tracking-tight to match PageShell h1 style
