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/layouts/MainLayout.tsx

@@ -145,6 +145,16 @@ const useStyles = makeStyles({
     padding: tokens.spacingVerticalS,
     flexShrink: 0,
   },
+  versionText: {
+    display: "block",
+    color: tokens.colorNeutralForeground4,
+    fontSize: "11px",
+    paddingLeft: tokens.spacingHorizontalS,
+    paddingRight: tokens.spacingHorizontalS,
+    paddingBottom: tokens.spacingVerticalXS,
+    whiteSpace: "nowrap",
+    overflow: "hidden",
+  },
 
   // Main content
   main: {
@@ -301,6 +311,11 @@ export function MainLayout(): React.JSX.Element {
 
         {/* Footer — Logout */}
         <div className={styles.sidebarFooter}>
+          {!collapsed && (
+            <Text className={styles.versionText}>
+              BanGUI v{__APP_VERSION__}
+            </Text>
+          )}
           <Tooltip
             content={collapsed ? "Sign out" : ""}
             relationship="label"