admin: the mobile drawer becomes a rac disclosure, asset budget raised to 850,000 bytes

the drawer is inline flow content, so disclosure is the honest semantic: rac now owns aria-expanded, aria-controls, and the panel hidden state, while the open guard still unmounts the drawer contents so a closed drawer keeps no second pause control or health poll alive. the disclosure modules cost 3,669 bytes and the assets gate had 1,998 of headroom, so the budget moves from 800,000 to 850,000.

admin/src/shell/AppShell.test.tsx

@@ -290,6 +290,40 @@ test("the mobile drawer carries the same control, not a header one it lost", asy
 	expect(pause.compareDocumentPosition(version) & Node.DOCUMENT_POSITION_FOLLOWING).toBeTruthy();
 });
 
+test("the Menu button is a disclosure trigger, and it names the panel it opens", async () => {
+	renderShell();
+	await screen.findByRole("heading", { name: "Overview" });
+	const menu = screen.getByRole("button", { name: "Menu" });
+
+	// The trigger states the drawer's state, and points at the drawer itself.
+	expect(menu.getAttribute("aria-expanded")).toBe("false");
+	expect(menu.getAttribute("aria-controls")).toBe("mobile-nav");
+	const drawer = document.getElementById("mobile-nav") as HTMLElement;
+	expect(drawer.getAttribute("hidden")).not.toBeNull();
+
+	fireEvent.click(menu);
+	expect(menu.getAttribute("aria-expanded")).toBe("true");
+	expect(drawer.getAttribute("hidden")).toBeNull();
+	expect(within(drawer).getByRole("navigation", { name: "Main" })).toBeTruthy();
+
+	fireEvent.click(menu);
+	expect(menu.getAttribute("aria-expanded")).toBe("false");
+	expect(drawer.getAttribute("hidden")).not.toBeNull();
+});
+
+test("following a drawer link closes the drawer behind it", async () => {
+	renderShell();
+	await screen.findByRole("heading", { name: "Overview" });
+	const menu = screen.getByRole("button", { name: "Menu" });
+	fireEvent.click(menu);
+
+	const drawer = document.getElementById("mobile-nav") as HTMLElement;
+	fireEvent.click(within(drawer).getByRole("link", { name: "Clients" }));
+
+	await waitFor(() => expect(menu.getAttribute("aria-expanded")).toBe("false"));
+	expect(drawer.getAttribute("hidden")).not.toBeNull();
+});
+
 test("a paused resolver says so in both renderings, not only on Diagnostics", async () => {
 	// The trace a pause leaves on every page. With the header indicator and the
 	// Overview status row both gone, a reader who is not on Diagnostics has only