Rename AdventureLog to Voyage and add fork attribution

- Replace all AdventureLog references with Voyage across ~102 files
  (7 case variants: AdventureLog, adventurelog, Adventurelog, ADVENTURELOG,
  AdventUrelog, AdventureLOG, adventure-log, adventure_log)
- Rename brand, static, and documentation assets to use voyage naming
- Rename install_adventurelog.sh → install_voyage.sh
- Update README.md and voyage_overview.md to credit AdventureLog as
  the upstream project and Sean Morley as its original creator

backend/server/adventures/views/recommendations_view.py

@@ -14,7 +14,7 @@ class RecommendationsViewSet(viewsets.ViewSet):
     permission_classes = [IsAuthenticated]
     OVERPASS_URL = "https://overpass-api.de/api/interpreter"
     NOMINATIM_URL = "https://nominatim.openstreetmap.org/search"
-    HEADERS = {'User-Agent': 'AdventureLog Server'}
+    HEADERS = {'User-Agent': 'Voyage Server'}
 
     # Quality thresholds
     MIN_GOOGLE_RATING = 3.0  # Minimum rating to include