feat(design): the channel menu's Tags and Priority submenus (C1, E28 S3e3b)

Tags A-Z as in-place checks (the menu stays open for the next); Priority
as the fixed steps 10 5 3 2 1 0, an off-scale current value ticked in its
place. A pick re-sorts the list at once, moving only that row
(placeByPriority, the server's order), and the table / card pager and
the focus follow it (DataTable and useCardPager take a reveal seq,
listNav.focusNavItem lands on the row's own "…", a virtualized card
revealed first). ActionMenu rows take check: many | one. The menu reads
the row fresh from the cache and keys its target by id.

frontend/src/components/ui/ActionMenu.dom.test.tsx

@@ -84,6 +84,37 @@ describe("ActionMenu", () => {
     await vi.waitFor(() => expect(onSelect).toHaveBeenCalledTimes(1));
   });
 
+  it("a 'many' check row toggles in place: the menu stays open and the focus stays on it", async () => {
+    const onSelect = vi.fn();
+    renderMenu([
+      { id: "rust", label: "rust", check: { kind: "many", checked: true }, onSelect },
+      { id: "go", label: "go", check: { kind: "many", checked: false }, onSelect: vi.fn() },
+    ]);
+    fireEvent.click(screen.getByRole("button", { name: "Catalog actions" }));
+    const rows = screen.getAllByRole("menuitemcheckbox", { hidden: true });
+    expect(rows.map((r) => r.getAttribute("aria-checked"))).toEqual(["true", "false"]);
+    fireEvent.click(rows[0]!);
+    // Synchronously — no close, no deferred act — and nothing closed around it.
+    expect(onSelect).toHaveBeenCalledTimes(1);
+    expect(screen.getAllByRole("menuitemcheckbox", { hidden: true })).toHaveLength(2);
+    await new Promise((r) => setTimeout(r, 0));
+    expect(screen.getAllByRole("menuitemcheckbox", { hidden: true })).toHaveLength(2);
+  });
+
+  it("a 'one' check row is a radio that picks and closes like any row", async () => {
+    const onSelect = vi.fn();
+    renderMenu([
+      { id: "10", label: "10", check: { kind: "one", checked: false }, onSelect },
+      { id: "5", label: "5", check: { kind: "one", checked: true }, onSelect: vi.fn() },
+    ]);
+    fireEvent.click(screen.getByRole("button", { name: "Catalog actions" }));
+    const rows = screen.getAllByRole("menuitemradio", { hidden: true });
+    expect(rows.map((r) => r.getAttribute("aria-checked"))).toEqual(["false", "true"]);
+    fireEvent.click(rows[0]!);
+    expect(screen.queryByRole("menuitemradio", { hidden: true })).toBeNull();
+    await vi.waitFor(() => expect(onSelect).toHaveBeenCalledTimes(1));
+  });
+
   it("a disabled item is inert — rendered disabled and never fires onSelect", () => {
     const onSelect = vi.fn();
     renderMenu([{ id: "sync", label: "Sync", onSelect, disabled: true }]);