Fix flex spot count in draft room Teams Drafted view

The flexSpots column in the database defaults to 0 and was never
populated, causing the Teams Drafted grid to always show "0 of 0 flex".
Calculate numFlexPicks dynamically in the loader as
max(0, draftRounds - seasonSports.length) so teams see the correct
flex count (e.g. 7 rounds - 5 sports = 2 flex).

https://claude.ai/code/session_01CSzF4aWuyppGBDqM4MJmhc

app/routes/leagues/$leagueId.draft.$seasonId.tsx

@@ -184,6 +184,7 @@ export async function loader(args: any) {
     userAutodraftSettings,
     isCommissioner: !!isCommissioner,
     currentUserId: userId,
+    numFlexPicks: Math.max(0, season.draftRounds - seasonSports.length),
   };
 }
 
@@ -200,6 +201,7 @@ export default function DraftRoom() {
     userAutodraftSettings,
     isCommissioner,
     currentUserId,
+    numFlexPicks,
   } = useLoaderData<typeof loader>();
   const { isConnected, connectionError, isReconnecting, on, off } = useDraftSocket(season.id, userTeam?.id);
   const {
@@ -999,7 +1001,7 @@ export default function DraftRoom() {
                     id: season.id,
                     name: `${season.year} Season`,
                     year: season.year,
-                    numFlexPicks: season.flexSpots,
+                    numFlexPicks: numFlexPicks,
                   }}
                 />
               </div>