As if the Giants weren’t already kicking themselves enough for their season gone wrong, consider this the insult added to the injury. They’re already stuck at home, watching the playoffs go on without them. Now they get to stare at an NFL championship games party that includes all the same guests from last year. All, that is, except for them. They wouldn’t have believed that was possible last May when they were getting their sparkly new diamond-encrusted wings and Justin Tuck was laying out his future for the Giants’ “dynasty.” He knew that dynasties aren’t supposed to happen in the NFL anymore, not with all the parity — or “competitive balance,” as the league likes to call it.