Fix JS/TS lint issues in web frontend

- Remove unused imports (ES6UnusedImports): AboutDialog, Dashboard, SetupWizard,
  jobs.astro, login.astro, settings.astro, stats.astro
- Prefix unused variables with underscore (JSUnusedLocalSymbols): _previousTheme,
  _lastJob, _loading, _detailLoading, _page, _success/_setSuccess
- Remove unused cn/clsx/twMerge from SystemStatus.tsx
- Add await to async calls (ES6MissingAwait) in JobManager, NotificationSettings,
  ScheduleSettings, SetupWizard, WatchFolders
- Add void keyword for ignored promises (JSIgnoredPromiseFromCall) in useEffect
  callbacks across Dashboard, FileSettings, HardwareSettings, JobManager, LogViewer,
  NotificationSettings, ResourceMonitor, ScheduleSettings, SetupWizard, StatsCharts,
  SystemSettings, SystemStatus, TranscodeSettings, WatchFolders
- CSS: Remove redundant background-color overridden by background shorthand;
  remove unused .btn selector
- HTML: Associate labels with form inputs via for/id attributes in login.astro

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

web/src/components/JobManager.tsx

@@ -68,7 +68,7 @@ export default function JobManager() {
     const [page, setPage] = useState(1);
     const [refreshing, setRefreshing] = useState(false);
     const [focusedJob, setFocusedJob] = useState<JobDetail | null>(null);
-    const [detailLoading, setDetailLoading] = useState(false);
+    const [_detailLoading, setDetailLoading] = useState(false);
     const [menuJobId, setMenuJobId] = useState<number | null>(null);
     const menuRef = useRef<HTMLDivElement | null>(null);
     const [confirmState, setConfirmState] = useState<{
@@ -121,7 +121,7 @@ export default function JobManager() {
     }, [activeTab, search, page]);
 
     useEffect(() => {
-        fetchJobs();
+        void fetchJobs();
         const interval = setInterval(fetchJobs, 5000); // Auto-refresh every 5s
         return () => clearInterval(interval);
     }, [fetchJobs]);
@@ -166,7 +166,7 @@ export default function JobManager() {
 
             if (res.ok) {
                 setSelected(new Set());
-                fetchJobs();
+                await fetchJobs();
             }
         } catch (e) {
             console.error("Batch action failed", e);
@@ -175,7 +175,7 @@ export default function JobManager() {
 
     const clearCompleted = async () => {
         await apiFetch("/api/jobs/clear-completed", { method: "POST" });
-        fetchJobs();
+        await fetchJobs();
     };
 
     const fetchJobDetails = async (id: number) => {
@@ -198,8 +198,8 @@ export default function JobManager() {
             const res = await apiFetch(`/api/jobs/${id}/${action}`, { method: "POST" });
             if (res.ok) {
                 if (action === "delete") setFocusedJob(null);
-                else fetchJobDetails(id);
-                fetchJobs();
+                else await fetchJobDetails(id);
+                await fetchJobs();
             }
         } catch (e) {
             console.error(`Action ${action} failed`, e);
@@ -446,7 +446,7 @@ export default function JobManager() {
                                                         <button
                                                             onClick={() => {
                                                                 setMenuJobId(null);
-                                                                fetchJobDetails(job.id);
+                                                                void fetchJobDetails(job.id);
                                                             }}
                                                             className="w-full px-4 py-2 text-left text-xs font-semibold text-helios-ink hover:bg-helios-surface-soft"
                                                         >