Fix project detail crash: replace dynamic hooks with single query

The project detail page called useQuery inside .map() to fetch file
requirements per round, violating React's rules of hooks. When
competitionRounds changed from [] to [round1, round2], the hook count
changed, causing React to crash with "Cannot read properties of
undefined (reading 'length')".

Fix: Add listRequirementsByRounds endpoint that accepts multiple
roundIds in one query, replacing the dynamic hook pattern with a
single stable useQuery call.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/server/routers/file.ts

@@ -818,6 +818,20 @@ export const fileRouter = router({
       })
     }),
 
+  /**
+   * List file requirements for multiple rounds in a single query.
+   * Avoids dynamic hook violations when fetching requirements per-round.
+   */
+  listRequirementsByRounds: protectedProcedure
+    .input(z.object({ roundIds: z.array(z.string()).max(50) }))
+    .query(async ({ ctx, input }) => {
+      if (input.roundIds.length === 0) return []
+      return ctx.prisma.fileRequirement.findMany({
+        where: { roundId: { in: input.roundIds } },
+        orderBy: { sortOrder: 'asc' },
+      })
+    }),
+
   /**
    * Create a file requirement for a stage (admin only)
    */