debug: log all continue statements in goal deviation calculation

- Log when using created_at as fallback for start_date
- Log when skipping due to missing created_at
- Log when skipping due to invalid date range (total_days <= 0)

This will reveal exactly why Körperfett and Zielgewicht are not added.

backend/placeholder_resolver.py

@@ -867,7 +867,9 @@ def _format_goals_behind(profile_id: str, n: int = 3) -> str:
                     created_at = g.get('created_at')
                     if created_at:
                         start_dt = date.fromisoformat(str(created_at).split('T')[0])
+                        print(f"[DEBUG]   → Using created_at as start_date: {start_dt}")
                     else:
+                        print(f"[DEBUG]   → Skipped: No start_date and no created_at")
                         continue  # Can't calculate without start date
 
                 target_dt = target_date if isinstance(target_date, date) else date.fromisoformat(str(target_date))
@@ -877,6 +879,7 @@ def _format_goals_behind(profile_id: str, n: int = 3) -> str:
                 elapsed_days = (today - start_dt).days
 
                 if total_days <= 0:
+                    print(f"[DEBUG]   → Skipped: Invalid date range (total_days={total_days})")
                     continue  # Invalid date range
 
                 expected_progress_pct = (elapsed_days / total_days) * 100