fix: sleep_avg_quality uses lowercase stage names

Problem: Schlafphasen werden lowercase gespeichert (deep, rem, light, awake),
aber get_sleep_avg_quality() prüfte Titlecase (Deep, REM) → 0% Match

Fix: Ändere Prüfung zu lowercase: ['deep', 'rem']

Jetzt wird {{sleep_avg_quality}} korrekt berechnet aus JSONB segments.

Quelle: backend/routers/sleep.py → phase_map speichert lowercase

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

backend/placeholder_resolver.py

@@ -347,7 +347,8 @@ def get_sleep_avg_quality(profile_id: str, days: int = 7) -> str:
         for row in rows:
             segments = row['sleep_segments']
             if segments:
-                deep_rem_min = sum(s.get('duration_min', 0) for s in segments if s.get('stage') in ['Deep', 'REM'])
+                # Note: stages are stored lowercase (deep, rem, light, awake)
+                deep_rem_min = sum(s.get('duration_min', 0) for s in segments if s.get('stage') in ['deep', 'rem'])
                 total_min = sum(s.get('duration_min', 0) for s in segments)
                 if total_min > 0:
                     quality_pct = (deep_rem_min / total_min) * 100