fix(a11y): use a single h1 on overview

src/App.test.tsx

@@ -75,6 +75,17 @@ describe("App layout", () => {
     expect(await screen.findByTestId("overview")).toBeInTheDocument();
   });
 
+  it("should expose a single level-one heading on the overview screen", async () => {
+    renderApp();
+
+    expect(await screen.findByTestId("overview")).toBeInTheDocument();
+    expect(screen.getAllByRole("heading", { level: 1 })).toHaveLength(1);
+    expect(screen.getByRole("heading", { level: 1, name: "PRism" })).toBeInTheDocument();
+    expect(
+      screen.getByRole("heading", { level: 2, name: "Review requests come first" }),
+    ).toBeInTheDocument();
+  });
+
   it("should render my-prs view", async () => {
     useDashboardStore.setState({ currentView: "mine" });
     renderApp();

src/components/Overview/Overview.test.tsx

@@ -158,6 +158,20 @@ describe("Overview", () => {
     expect(screen.getByText("PR #2")).toBeInTheDocument();
   });
 
+  it("should use a level-two heading for the priority lane title", () => {
+    setupMock(
+      makeDashboard({
+        reviewRequests: [makePr(1)],
+      }),
+    );
+
+    renderWithProviders(<Overview />);
+
+    expect(
+      screen.getByRole("heading", { name: "Review requests come first", level: 2 }),
+    ).toBeInTheDocument();
+  });
+
   it("should render my PRs section", () => {
     setupMock(
       makeDashboard({

src/components/Overview/Overview.tsx

@@ -122,7 +122,7 @@ export function Overview(): ReactElement {
               <p className="text-[11px] font-semibold uppercase tracking-[0.24em] text-accent">
                 Priority lane
               </p>
-              <h1 className="text-lg font-semibold text-white">Review requests come first</h1>
+              <h2 className="text-lg font-semibold text-white">Review requests come first</h2>
               <p className="max-w-2xl text-sm text-dim">
                 Surface the PRs that need your attention now so approvals and requested changes do
                 not get buried under passive updates.