fix(data): add trailing newline to synced JSON (pre-commit end-of-file-fixer)

The leaderboard sync (#54) wrote category_scores.json, leaderboard.json and
routers.json without a final newline, failing the end-of-file-fixer hook on
main. No data changes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RSUYhdCawUgo1zFJ2WCuir

Author: jamesbond19925-spec

src/data/routerMetrics/category_scores.json

@@ -26979,4 +26979,4 @@
       }
     }
   }
-}
+}

src/data/routerMetrics/leaderboard.json

@@ -351,4 +351,4 @@
     "Accuracy": 32.01,
     "Cost per 1k": 0.07
   }
-]
+]

src/data/routers.json

@@ -550,4 +550,4 @@
       "deepseek/deepseek-v4-flash"
     ]
   }
-}
+}