admin: live query detail becomes a modal, live/history and period pickers become tabs and radios, client delete confirms in a dialog

the streamed-query detail panel is now a rac modal dialog with focus containment and restore. the live/history switch is rac tabs driven by the url, the overview period picker is a rac radio group, and the clients delete flow uses the shared confirm dialog; an authority turn keeps the dialog open and withdraws only the destructive action.

admin/src/features/activity/ActivityPage.test.tsx

@@ -12,6 +12,7 @@ import { createAppRouter } from "@/routes";
 import { health } from "@/lib/healthFixture";
 import type { Client, Coverage, QueriesPage, QueryRow } from "@/lib/types";
 import { queryRow } from "@/features/provenance/provenanceFixture";
+import { FakeEventSource } from "./fakeEventSource";
 
 function client(id: number, ip: string, name: string, learnedName: string): Client {
 	return {
@@ -544,6 +545,40 @@ test("the policy simulation is reachable from the header, with no rows to click
 	expect(history.location.pathname).toBe("/activity/test");
 });
 
+test("the mode switch is a tab list whose selection is the url, and it keeps the filters", async () => {
+	// Live opens a stream as soon as its panel mounts, so the switch cannot be
+	// exercised without one; the fake stands in for the browser's EventSource.
+	vi.stubGlobal(
+		"EventSource",
+		class {
+			constructor(url: string) {
+				return new FakeEventSource(url) as unknown as EventSource;
+			}
+		},
+	);
+	const { history } = renderPage("/activity?mode=history&domain=ads&blocked=true");
+	await screen.findByText("ads.example");
+
+	const tabs = within(screen.getByRole("tablist", { name: "Activity mode" }));
+	expect(tabs.getAllByRole("tab").map((tab) => tab.textContent)).toEqual(["History", "Live"]);
+	expect(tabs.getByRole("tab", { name: "History", selected: true })).toBeTruthy();
+	expect(tabs.getByRole("tab", { name: "Live", selected: false })).toBeTruthy();
+
+	fireEvent.click(tabs.getByRole("tab", { name: "Live" }));
+
+	await waitFor(() => expect(history.location.search).toContain("mode=live"));
+	// The investigation survives the switch: both filters are still in the URL.
+	expect(history.location.search).toContain("domain=ads");
+	expect(history.location.search).toContain("blocked=true");
+	expect(
+		within(screen.getByRole("tablist", { name: "Activity mode" })).getByRole("tab", {
+			name: "Live",
+			selected: true,
+		}),
+	).toBeTruthy();
+	expect(await screen.findByText(/these filters apply to history only/)).toBeTruthy();
+});
+
 test("Clear empties the url as well as the form", async () => {
 	const { history } = renderPage("/activity?mode=history&domain=ads&blocked=true");
 	await screen.findByText("ads.example");