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/lib/components/TOTPModal.svelte

@@ -56,7 +56,7 @@
 		const data = await res.json();
 		if (res.status == 404) {
 			secret = data.meta.secret;
-			totpUrl = `otpauth://totp/AdventureLog:${user?.username}?secret=${secret}&issuer=AdventureLog`;
+			totpUrl = `otpauth://totp/Voyage:${user?.username}?secret=${secret}&issuer=Voyage`;
 			generateQRCode(totpUrl);
 		} else if (res.ok) {
 			close();