fix(auto-update): revert checkNow to use performCheck (GitHub API) instead of electron-updater IPC

checkNow was calling bridge.checkForUpdate() which invokes updater.checkForUpdates()
via IPC. startAutoCheck() in the main process already calls checkForUpdates() on a
5s timer, and if that network request is still pending, the concurrent IPC call from
checkNow hangs indefinitely, causing the UI to be stuck in "checking" state forever.

Per the original design spec, checkNow should use performCheck() (GitHub API) directly.
This is completely independent of electron-updater's internal state machine, so it
never conflicts with the background startAutoCheck(). performCheck handles isCheckingRef,
isChecking, hasUpdate, and latestRelease; checkNow only manages manualCheckStatus.

application/state/useUpdateCheck.ts

@@ -235,117 +235,41 @@ export function useUpdateCheck(): UseUpdateCheckResult {
   }, []);
 
   const checkNow = useCallback(async (): Promise<null> => {
-    // Prevent concurrent checks (same guard used by performCheck)
+    // Prevent concurrent checks (performCheck owns isCheckingRef)
     if (isCheckingRef.current) {
       debugLog('checkNow: already checking, skipping');
       return null;
     }
 
-    isCheckingRef.current = true;
+    // Immediately reflect 'checking' in the UI
     setUpdateState((prev) => ({
       ...prev,
-      isChecking: true,
       manualCheckStatus: 'checking',
       error: null,
     }));
 
-    try {
-      const bridge = netcattyBridge.get();
-      const result = await bridge?.checkForUpdate?.();
-
-      // Bridge unavailable (no Electron context)
-      if (!result) {
-        setUpdateState((prev) => ({
-          ...prev,
-          isChecking: false,
-          manualCheckStatus: 'error',
-          error: 'Update check unavailable',
-        }));
-        return null;
-      }
-
-      // Platform does not support electron-updater (Linux deb/rpm/snap) →
-      // fall back to GitHub API for version awareness only (no auto-download)
-      if (result?.supported === false) {
-        // Read version from ref to avoid stale closure
-        const effectiveVersion = IS_UPDATE_DEMO_MODE ? '0.0.1' : currentVersionRef.current;
-        if (!effectiveVersion || effectiveVersion === '0.0.0') {
-          setUpdateState((prev) => ({
-            ...prev,
-            isChecking: false,
-            manualCheckStatus: 'up-to-date',
-          }));
-          return null;
-        }
-        // Temporarily release the ref so performCheck can use its own guard
-        isCheckingRef.current = false;
-        const githubResult = await performCheck(effectiveVersion);
-        // performCheck already updates the state (hasUpdate, latestRelease, etc.)
-        // We only need to set manualCheckStatus from the result.
-        // isCheckingRef is now false (performCheck's finally cleared it), so finally
-        // block below is harmless.
-        setUpdateState((prev) => ({
-          ...prev,
-          isChecking: false,
-          manualCheckStatus: githubResult?.hasUpdate ? 'available' : 'up-to-date',
-        }));
-        return null;
-      }
-
-      // IPC returned an error
-      if (result?.error) {
-        setUpdateState((prev) => ({
-          ...prev,
-          isChecking: false,
-          manualCheckStatus: 'error',
-          error: result.error ?? 'Update check failed',
-        }));
-        return null;
-      }
-
-      if (result?.available && result.version) {
-        // autoDownload=true: electron-updater starts download immediately.
-        // The onUpdateAvailable IPC event will set autoDownloadStatus='downloading'.
-        // We set hasUpdate=true and populate latestRelease so UI can show version.
-        const now = Date.now();
-        localStorageAdapter.writeNumber(STORAGE_KEY_UPDATE_LAST_CHECK, now);
-        setUpdateState((prev) => ({
-          ...prev,
-          isChecking: false,
-          manualCheckStatus: 'available',
-          hasUpdate: true,
-          lastCheckedAt: now,
-          latestRelease: prev.latestRelease ?? {
-            version: result.version!,
-            tagName: `v${result.version}`,
-            name: `v${result.version}`,
-            body: typeof result.releaseNotes === 'string' ? result.releaseNotes : '',
-            htmlUrl: '',
-            publishedAt: result.releaseDate ?? new Date().toISOString(),
-            assets: [],
-          },
-        }));
-      } else {
-        setUpdateState((prev) => ({
-          ...prev,
-          isChecking: false,
-          manualCheckStatus: 'up-to-date',
-        }));
-      }
-
-      return null;
-    } catch (err) {
-      const msg = err instanceof Error ? err.message : 'Unknown error';
+    // Skip check for dev/invalid builds (demo mode overrides to '0.0.1' inside performCheck)
+    const effectiveVersion = IS_UPDATE_DEMO_MODE ? '0.0.1' : currentVersionRef.current;
+    if (!effectiveVersion || effectiveVersion === '0.0.0') {
       setUpdateState((prev) => ({
         ...prev,
-        isChecking: false,
-        manualCheckStatus: 'error',
-        error: msg,
+        manualCheckStatus: 'up-to-date',
       }));
       return null;
-    } finally {
-      isCheckingRef.current = false;
     }
+
+    // Delegate to performCheck (GitHub API) — completely independent of
+    // electron-updater's startAutoCheck() in the main process.
+    // performCheck sets isCheckingRef, isChecking, hasUpdate, latestRelease.
+    const result = await performCheck(effectiveVersion);
+
+    setUpdateState((prev) => ({
+      ...prev,
+      manualCheckStatus:
+        result === null ? 'error' : result.hasUpdate ? 'available' : 'up-to-date',
+    }));
+
+    return null;
   }, [performCheck]);
 
   const dismissUpdate = useCallback(() => {