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

frontend/src/routes/users/+page.svelte

@@ -9,7 +9,7 @@
 	console.log(users);
 </script>
 
-<h1 class="text-center font-bold text-4xl mb-4">AdventureLog {$t('navbar.users')}</h1>
+<h1 class="text-center font-bold text-4xl mb-4">Voyage {$t('navbar.users')}</h1>
 <div class="flex flex-wrap gap-4 mr-4 justify-center content-center">
 	{#each users as user (user.uuid)}
 		<UserCard {user} />