Eliminates the per-page <ConfirmDialog @ref="_confirmDialog"
ConfirmButtonClass="btn-danger" /> boilerplate. Pages now inject
IDialogService and call ConfirmAsync(title, message, danger: true)
programmatically.
New scoped service holds a single active dialog (throws on nested
calls), with a global DialogHost mounted once in MainLayout that
renders the modal markup, owns body scroll-lock via Bootstrap's
modal-open class, traps focus on the modal element, and handles
Escape-to-cancel.
Same service also exposes PromptAsync, used to replace the bespoke
NewFolderDialog. Both ConfirmDialog and NewFolderDialog components
are deleted — their callers (~13 pages across Admin/Design/Deployment
/Monitoring) now go through the service.
DiffDialog stays as-is — different use case (before/after content).
bUnit tests in TopologyPageTests, DataConnectionsPageTests, and
TemplatesPageTests register IDialogService in their service
collection.
Also: a top-of-file Razor comment on Sites.razor pointing future
implementers at it as the reference list-page pattern.