Fix Failures tooltip wording; move Service Health to top of Server tab

Task 2: rename 'Failures:' label to 'Failed Attempts:' and update tooltip
to 'Total failed authentication attempts currently tracked by fail2ban
across all active jails' — more accurate than 'Currently failing IPs'.

Task 3: move <ServerHealthSection /> to the top of ServerTab so users
see connectivity status before scrolling through all settings fields.

frontend/src/components/__tests__/ServerStatusBar.test.tsx

@@ -136,6 +136,8 @@ describe("ServerStatusBar", () => {
     expect(screen.getByText("4")).toBeInTheDocument();
     expect(screen.getByText("21")).toBeInTheDocument();
     expect(screen.getByText("99")).toBeInTheDocument();
+    // Verify the "Failed Attempts:" label (renamed from "Failures:").
+    expect(screen.getByText("Failed Attempts:")).toBeInTheDocument();
   });
 
   it("renders an error message when the status fetch fails", () => {