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/static/icons/phosphor.svg

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