fix: correct online state on startup instead of waiting for a network event

[setchy]

Problem
TanStack Query's onlineManager initializes to online: true regardless of the device's actual network state, and only self-corrects when the browser fires a native online/offline event. Since browsers only emit events on transitions, a device that's already offline when Gitify launches (airplane mode, VPN down, etc.) never gets one — so the app incorrectly believes it's online from the first render, fires the notifications query, and only discovers it's offline after that query fails and retries.

Fix
Added a single onlineManager.setOnline(navigator.onLine) call at the start of useOnlineStatus's mount effect, before the existing subscription logic. This actively force-corrects onlineManager's state to match reality on startup, instead of passively waiting for a future browser event that may never come.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[afonsojramos]

Verified the offline cold-start path and the follow-ups pushed here.

Moving the correction to queryClient.ts module scope means it runs at import, before the client exists and therefore before any query can fire — so it no longer depends on GlobalEffects rendering ahead of the router or on useOnlineStatus() being declared above useNotifications(). Seeding useState from onlineManager.isOnline() keeps a single source of truth and drops the one frame that painted as online.

Also replaced the confirms onlineManager as online when the device starts online case: it passed with the production line deleted (onlineManager already defaults to true, and setOnline only notifies on change). The replacements start from the opposite state in both directions and I confirmed both fail without the fix.