chore: complete rebranding from seanmorley15 to Alex-Wiesner/voyage

Replace all seanmorley15/Voyage repo URLs, ghcr.io/seanmorley15 container
image references, seanmorley.com/sponsor and buymeacoffee links with
the new repo (github.com/Alex-Wiesner/voyage) and new GHCR images
(ghcr.io/alex-wiesner/voyage-*). Attribution to original AdventureLog
author Sean Morley is preserved.

docker-compose.yml

@@ -1,7 +1,7 @@
 services:
   web:
     #build: ./frontend/
-    image: ghcr.io/seanmorley15/voyage-frontend:latest
+    image: ghcr.io/alex-wiesner/voyage-frontend:latest
     container_name: voyage-frontend
     restart: unless-stopped
     env_file: .env
@@ -20,7 +20,7 @@ services:
 
   server:
     #build: ./backend/
-    image: ghcr.io/seanmorley15/voyage-backend:latest
+    image: ghcr.io/alex-wiesner/voyage-backend:latest
     container_name: voyage-backend
     restart: unless-stopped
     env_file: .env