feat: frontend Actions Tab with structured API, assign/create/remove dialogs (Task 3.3)

- ActionsTab rewritten with master/detail layout (mirrors FiltersTab)
- New AssignActionDialog and CreateActionDialog components
- ActionConfig type extended with active, used_by_jails, source_file, has_local_override
- New API functions: fetchActions, fetchAction, updateAction, createAction, deleteAction, assignActionToJail, removeActionFromJail
- useActionConfig updated to use new structured endpoints
- index.ts barrel exports updated

frontend/src/components/config/index.ts

@@ -10,6 +10,8 @@ export { ActionForm } from "./ActionForm";
 export type { ActionFormProps } from "./ActionForm";
 export { ActivateJailDialog } from "./ActivateJailDialog";
 export type { ActivateJailDialogProps } from "./ActivateJailDialog";
+export { AssignActionDialog } from "./AssignActionDialog";
+export type { AssignActionDialogProps } from "./AssignActionDialog";
 export { AssignFilterDialog } from "./AssignFilterDialog";
 export type { AssignFilterDialogProps } from "./AssignFilterDialog";
 export { AutoSaveIndicator } from "./AutoSaveIndicator";
@@ -18,6 +20,8 @@ export { ConfFilesTab } from "./ConfFilesTab";
 export type { ConfFilesTabProps } from "./ConfFilesTab";
 export { ConfigListDetail } from "./ConfigListDetail";
 export type { ConfigListDetailProps } from "./ConfigListDetail";
+export { CreateActionDialog } from "./CreateActionDialog";
+export type { CreateActionDialogProps } from "./CreateActionDialog";
 export { CreateFilterDialog } from "./CreateFilterDialog";
 export type { CreateFilterDialogProps } from "./CreateFilterDialog";
 export { ExportTab } from "./ExportTab";