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

cdn/docker-compose.yml

@@ -1,7 +1,7 @@
 services:
   cdn:
     build: .
-    container_name: adventurelog-cdn
+    container_name: voyage-cdn
     ports:
       - "8080:80"
     restart: unless-stopped