fix: group project files by round in admin project detail

- Sort files by round sortOrder first (via requirement.round.sortOrder)
- Admin project detail now uses grouped file view with round headers
- Files without a round requirement appear under "General" group

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

src/server/routers/file.ts

@@ -358,7 +358,11 @@ export const fileRouter = router({
             },
           },
         },
-        orderBy: [{ fileType: 'asc' }, { createdAt: 'asc' }],
+        orderBy: [
+          { requirement: { round: { sortOrder: 'asc' } } },
+          { fileType: 'asc' },
+          { createdAt: 'asc' },
+        ],
       })
     }),