Refactored AssignActionDialog and AssignFilterDialog to only render
dialog content when open=true. This prevents useJails() from being called
when dialogs are closed, eliminating unnecessary GET /api/jails requests.
Implementation uses inner components (AssignActionDialogInner,
AssignFilterDialogInner) that are only mounted when the dialog is open.
The Dialog wrapper remains in the outer component to preserve Fluent UI
animation behavior.
Fixed test setup for AssignFilterDialog to properly call
assignFilterToJail from the mocked onAssign callback.
Fixes TASK-BUG-08.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>