fix: address prerelease workflow review bugs

- Type checkVersion() with VersionInfo interface; fixes TS errors in
  checkAndNotifyVersion() where object type blocked property access
- Don't cache fallback on !resp.ok or fetch throw; prevents a transient
  GitHub outage from poisoning the 5-min version cache
- Guard parseInt result with Number.isFinite() in compareVersions;
  malformed -pre.abc tags no longer silently compare as equal via NaN
- Pre-compute stripped versions before sort in checkVersion(); avoids
  mutating input array and redundant replace() calls in comparator
- Bump GitHub releases fetch from per_page=20 to per_page=100
- Store appVersion in authStore; populate from App.tsx getAppConfig call
  and remove redundant getAppConfig fetch in Navbar useEffect
- Type GitHubPanel error/expanded state as string|null and Record<number,boolean>

client/src/components/Admin/GitHubPanel.tsx

@@ -16,8 +16,8 @@ export default function GitHubPanel({ isPrerelease = false }: { isPrerelease?: b
   const { t, language } = useTranslation()
   const [releases, setReleases] = useState<GithubRelease[]>([])
   const [loading, setLoading] = useState(true)
-  const [error, setError] = useState(null)
-  const [expanded, setExpanded] = useState({})
+  const [error, setError] = useState<string | null>(null)
+  const [expanded, setExpanded] = useState<Record<number, boolean>>({})
   const [page, setPage] = useState(1)
   const [hasMore, setHasMore] = useState(true)
   const [loadingMore, setLoadingMore] = useState(false)