feat: Add MongoDB backups repository with comprehensive documentation

Backups included:
- mongodb-20251022-093651.tar.gz (233 MB, 24 databases)
- backup_20250928_214747.tar.gz (233 MB)

Features:
- Complete MongoDB dumps from site11_mongodb container
- Compressed tar.gz format for efficient storage
- Comprehensive README with restore procedures
- Backup verification and automation guides
- Emergency recovery documentation

Database coverage:
- ai_writer_db (461 MB) - Main content database
- news_api_db - News API and outlets
- Service databases (AI, Apple, Crypto, Google, Samsung, LG, WSJ, Musk, Korea)
- Artist databases (NCT, TWICE, ENHYPEN, IVE, Stray Kids, BLACKPINK)
- OAuth and pipeline databases

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,6 @@
+# Ignore uncompressed backup directories
+mongodb-*/
+20*/
+
+# Keep compressed backups only
+# *.tar.gz files will be tracked