Fix send_slack_report: encoding and default run_date

- Add UTF-8 stdout wrapper (fixes emoji encoding on Windows)
- Default run_date to today (run.py saves snapshots with today's date,
  not yesterday's)

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

send_slack_report.py

@@ -1,4 +1,8 @@
 """Re-send yesterday's Slack report from Baserow snapshots."""
+import sys
+import io
+sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding="utf-8", line_buffering=True)
+
 import json
 from datetime import datetime, timedelta
 
@@ -18,7 +22,7 @@ def _extract_vertical(name: str) -> str:
 
 def main():
     import sys as _sys
-    run_date = _sys.argv[1] if len(_sys.argv) > 1 else (datetime.now() - timedelta(days=1)).strftime("%Y-%m-%d")
+    run_date = _sys.argv[1] if len(_sys.argv) > 1 else datetime.now().strftime("%Y-%m-%d")
     print(f"Reenviando informe para {run_date}...")
 
     meta = MetaAdsClient()