refactor: consolidate blockchain explorer into single app and update backup ignore patterns

- Remove standalone explorer-web app (README, HTML, package files)
- Add /web endpoint to blockchain-explorer for web interface access
- Update .gitignore to exclude application backup archives (*.tar.gz, *.zip)
- Add backup documentation files to .gitignore (BACKUP_INDEX.md, README.md)
- Consolidate explorer functionality into main blockchain-explorer application

cli/configs/multichain_config.yaml

@@ -9,7 +9,7 @@ nodes:
   
   aitbc-main:
     id: aitbc-main
-    endpoint: http://10.1.223.93:8545
+    endpoint: http://localhost:8546
     timeout: 30
     retry_count: 3
     max_connections: 10