docs: Add database backup documentation

scripts/BACKUP-INFO.md

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+# Database Backup Information
+
+## Automatic Backups
+
+The `sync-database-schema.sh` script automatically creates backups before making any schema changes to the production database.
+
+### Backup Location
+
+```
+/root/maternal-app/backups/db-schema-sync/
+```
+
+### Backup Naming Convention
+
+```
+parentflow_schema_backup_YYYYMMDD_HHMMSS.sql.gz
+```
+
+Example: `parentflow_schema_backup_20251008_155030.sql.gz`
+
+### How It Works
+
+1. **Pre-flight Analysis**: Script analyzes both databases to detect differences
+2. **Backup Creation**: If changes will be made, creates compressed schema backup
+3. **Automatic Cleanup**: Keeps only the 10 most recent backups
+4. **Sync Process**: Proceeds with schema synchronization
+5. **Summary**: Shows backup location and restore command
+
+### Restoring from Backup
+
+If you need to restore a backup:
+
+```bash
+# List available backups
+ls -lh /root/maternal-app/backups/db-schema-sync/
+
+# Restore a specific backup
+gunzip -c /root/maternal-app/backups/db-schema-sync/parentflow_schema_backup_YYYYMMDD_HHMMSS.sql.gz | \
+  PGPASSWORD=a3ppq psql -h 10.0.0.207 -U postgres -d parentflow
+```
+
+### Backup Details
+
+- **Type**: Schema-only backup (no data)
+- **Format**: Plain SQL (compressed with gzip)
+- **Size**: Typically 50-200 KB compressed
+- **Retention**: Last 10 backups kept automatically
+- **Created**: Only when changes will be made (not in dry-run mode)
+
+### Manual Backup
+
+To create a manual backup:
+
+```bash
+# Schema-only backup
+PGPASSWORD=a3ppq pg_dump -h 10.0.0.207 -U postgres -d parentflow \
+  --schema-only --no-owner --no-acl -f backup_$(date +%Y%m%d_%H%M%S).sql
+
+# Full backup (schema + data)
+PGPASSWORD=a3ppq pg_dump -h 10.0.0.207 -U postgres -d parentflow \
+  -f backup_full_$(date +%Y%m%d_%H%M%S).sql
+
+# Compress it
+gzip backup_*.sql
+```
+
+### Testing Backup Restoration
+
+Always test backup restoration in a safe environment:
+
+```bash
+# Create test database
+PGPASSWORD=a3ppq psql -h 10.0.0.207 -U postgres -c "CREATE DATABASE parentflow_test;"
+
+# Restore backup to test database
+gunzip -c /root/maternal-app/backups/db-schema-sync/parentflow_schema_backup_YYYYMMDD_HHMMSS.sql.gz | \
+  PGPASSWORD=a3ppq psql -h 10.0.0.207 -U postgres -d parentflow_test
+
+# Verify
+PGPASSWORD=a3ppq psql -h 10.0.0.207 -U postgres -d parentflow_test -c "\dt"
+
+# Drop test database when done
+PGPASSWORD=a3ppq psql -h 10.0.0.207 -U postgres -c "DROP DATABASE parentflow_test;"
+```
+
+### Troubleshooting
+
+**Backup fails with "version mismatch"**:
+- Script automatically falls back to SQL-based backup
+- This is normal and safe
+
+**Not enough disk space**:
+```bash
+# Check disk space
+df -h /root/maternal-app/backups/
+
+# Manual cleanup
+rm /root/maternal-app/backups/db-schema-sync/old_backup_file.sql.gz
+```
+
+**Restore fails**:
+- Ensure target database exists
+- Check PostgreSQL logs: `/var/log/postgresql/`
+- Verify backup file is not corrupted: `gunzip -t backup.sql.gz`
+
+### Best Practices
+
+1. **Before major changes**: Always run with `--dry-run` first
+2. **Keep external backups**: Don't rely solely on automatic backups
+3. **Test restores**: Periodically test backup restoration
+4. **Monitor disk space**: Ensure adequate space in backup directory
+5. **Document changes**: Keep notes on what changed and when
+
+### See Also
+
+- Main script documentation: [README-SYNC-SCHEMA.md](README-SYNC-SCHEMA.md)
+- Database schema docs: `/docs/maternal-app-db-migrations.md`