Show BanGUI app version in sidebar, fix version tooltips

- Inject __APP_VERSION__ at build time via vite.config.ts define (reads
  frontend/package.json#version); declare the global in vite-env.d.ts.
- Render 'BanGUI v{__APP_VERSION__}' in the sidebar footer (MainLayout)
  when expanded; hidden when collapsed.
- Rename fail2ban version tooltip to 'fail2ban daemon version' in
  ServerStatusBar so it is visually distinct from the app version.
- Sync frontend/package.json version (0.9.0 → 0.9.3) to match
  Docker/VERSION; update release.sh to keep them in sync on every bump.
- Add vitest define stub for __APP_VERSION__ so tests compile cleanly.
- Add ServerStatusBar and MainLayout test suites (10 new test cases).

frontend/src/components/ServerStatusBar.tsx

@@ -109,7 +109,7 @@ export function ServerStatusBar(): React.JSX.Element {
       {/* Version                                                          */}
       {/* ---------------------------------------------------------------- */}
       {status?.version != null && (
-        <Tooltip content="fail2ban version" relationship="description">
+        <Tooltip content="fail2ban daemon version" relationship="description">
           <Text size={200} className={styles.statValue}>
             v{status.version}
           </Text>

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

@@ -0,0 +1,151 @@
+/**
+ * Tests for the ServerStatusBar component.
+ *
+ * Covers loading state, online / offline rendering, and correct tooltip
+ * wording that distinguishes the fail2ban daemon version from the BanGUI
+ * application version.
+ */
+
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { render, screen } from "@testing-library/react";
+import { FluentProvider, webLightTheme } from "@fluentui/react-components";
+import { ServerStatusBar } from "../ServerStatusBar";
+
+// ---------------------------------------------------------------------------
+// Mock useServerStatus so tests never touch the network.
+// ---------------------------------------------------------------------------
+
+vi.mock("../../hooks/useServerStatus");
+
+import { useServerStatus } from "../../hooks/useServerStatus";
+
+const mockedUseServerStatus = vi.mocked(useServerStatus);
+
+function renderBar(): void {
+  render(
+    <FluentProvider theme={webLightTheme}>
+      <ServerStatusBar />
+    </FluentProvider>,
+  );
+}
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+describe("ServerStatusBar", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("shows a spinner while the initial load is in progress", () => {
+    mockedUseServerStatus.mockReturnValue({
+      status: null,
+      loading: true,
+      error: null,
+      refresh: vi.fn(),
+    });
+    renderBar();
+    // The status-area spinner is labelled "Checking\u2026".
+    expect(screen.getByText("Checking\u2026")).toBeInTheDocument();
+  });
+
+  it("renders an Online badge when the server is reachable", () => {
+    mockedUseServerStatus.mockReturnValue({
+      status: {
+        online: true,
+        version: "1.1.0",
+        active_jails: 3,
+        total_bans: 10,
+        total_failures: 5,
+      },
+      loading: false,
+      error: null,
+      refresh: vi.fn(),
+    });
+    renderBar();
+    expect(screen.getByText("Online")).toBeInTheDocument();
+  });
+
+  it("renders an Offline badge when the server is unreachable", () => {
+    mockedUseServerStatus.mockReturnValue({
+      status: {
+        online: false,
+        version: null,
+        active_jails: 0,
+        total_bans: 0,
+        total_failures: 0,
+      },
+      loading: false,
+      error: null,
+      refresh: vi.fn(),
+    });
+    renderBar();
+    expect(screen.getByText("Offline")).toBeInTheDocument();
+  });
+
+  it("displays the daemon version string when available", () => {
+    mockedUseServerStatus.mockReturnValue({
+      status: {
+        online: true,
+        version: "1.2.3",
+        active_jails: 1,
+        total_bans: 0,
+        total_failures: 0,
+      },
+      loading: false,
+      error: null,
+      refresh: vi.fn(),
+    });
+    renderBar();
+    expect(screen.getByText("v1.2.3")).toBeInTheDocument();
+  });
+
+  it("does not render the version element when version is null", () => {
+    mockedUseServerStatus.mockReturnValue({
+      status: {
+        online: false,
+        version: null,
+        active_jails: 0,
+        total_bans: 0,
+        total_failures: 0,
+      },
+      loading: false,
+      error: null,
+      refresh: vi.fn(),
+    });
+    renderBar();
+    // No version string should appear in the document.
+    expect(screen.queryByText(/^v\d/)).not.toBeInTheDocument();
+  });
+
+  it("shows jail / ban / failure counts when the server is online", () => {
+    mockedUseServerStatus.mockReturnValue({
+      status: {
+        online: true,
+        version: "1.0.0",
+        active_jails: 4,
+        total_bans: 21,
+        total_failures: 99,
+      },
+      loading: false,
+      error: null,
+      refresh: vi.fn(),
+    });
+    renderBar();
+    expect(screen.getByText("4")).toBeInTheDocument();
+    expect(screen.getByText("21")).toBeInTheDocument();
+    expect(screen.getByText("99")).toBeInTheDocument();
+  });
+
+  it("renders an error message when the status fetch fails", () => {
+    mockedUseServerStatus.mockReturnValue({
+      status: null,
+      loading: false,
+      error: "Network error",
+      refresh: vi.fn(),
+    });
+    renderBar();
+    expect(screen.getByText("Network error")).toBeInTheDocument();
+  });
+});