Session 2026-04-19: Navigation, Kompass, Übungsfortschritt

Routen-Navigation:
- POI-Marker: farbige Kreise mit Phosphor-Icons (wie Hauptkarte)
- Screensaver: Navi-Pfeil dreht sich via DeviceOrientationEvent (iOS+Android)
- Pfeil-Dämpfung: EMA α=0.12 mit Wrap-Around
- GPS-Distanz-Bug: Fortschritt nur wenn <500m zur Route
- fitBounds: User-Position nur wenn <20km von Route
- Screensaver: "zur Route" vs "verbleibend" kontextabhängig
- Richtungspfeile entlang Route (blau, max 7 Stück)
- Umkehren ins Route-Detail verschoben, Detail-Map rebuildet sich
- rk-header z-index:10 (Leaflet-Tiles liefen drüber)
- 2-Sek. Screensaver-Entsperrung

km-Tracking:
- route_walks Tabelle
- POST /api/routes/{id}/walked (≥50%)
- total_km = erstellte Routes + gelaufene route_walks
- Toast bei neuem Badge

Übungsfortschritt:
- exercise_progress + training_plan_progress Tabellen
- GET/POST /api/training/progress, /plan-progress, /suggestions
- uebungen.js: API-first + localStorage-Fallback + Auto-Migration
- Empfehlungs-Banner (regelbasiert)
- Toast bei "sitzt"

backend/routes/auth.py

@@ -116,14 +116,20 @@ async def logout(response: Response):
 async def get_referral_info(user=Depends(get_current_user)):
     with db() as conn:
         row = conn.execute(
-            "SELECT referral_code, (SELECT COUNT(*) FROM users WHERE referred_by=?) AS count FROM users WHERE id=?",
+            """SELECT referral_code,
+                      COALESCE((SELECT COUNT(*) FROM users WHERE referred_by=?), 0) AS count
+               FROM users WHERE id=?""",
             (user['id'], user['id'])
         ).fetchone()
+        code = row["referral_code"] if row else None
+        if not code:
+            code = _gen_referral_code()
+            conn.execute("UPDATE users SET referral_code=? WHERE id=?", (code, user['id']))
     base = os.getenv("APP_URL", "https://banyaro.app")
     return {
-        "code":  row["referral_code"],
-        "count": row["count"],
-        "link":  f"{base}/?ref={row['referral_code']}",
+        "code":  code,
+        "count": row["count"] if row else 0,
+        "link":  f"{base}/?ref={code}",
     }