fix(desktop): remove capability guard from update install button

The update banner's "restart & install" button silently did nothing
because the renderer-side install() checked applyMode before calling
IPC. If the capability was fetched before updateManager initialized,
applyMode was "none" and the guard blocked the call permanently.

Remove the redundant guard — the main process IPC handler already
has its own null check on updateManager. The button is only visible
when the update is in "ready" state, so the install action is always
valid at that point.

Author: lefarcen

apps/desktop/src/hooks/use-auto-update.ts

@@ -375,13 +375,6 @@ export function useAutoUpdate(options?: {
   }, [state.capability]);
 
   const install = useCallback(async () => {
-    if (
-      state.capability?.applyMode !== "in-app" &&
-      state.capability?.applyMode !== "external-installer"
-    ) {
-      return;
-    }
-
     let previousPhase: Exclude<UpdatePhase, "installing"> = "ready";
 
     setState((prev) => {
@@ -394,7 +387,7 @@ export function useAutoUpdate(options?: {
     } catch {
       // Errors are delivered via the update:error event
     }
-  }, [state.capability]);
+  }, []);
 
   const dismiss = useCallback(() => {
     setState((prev) => ({