This commit implements fixes for three independent bugs in the fail2ban configuration and integration layer:
1. Task 1: Detect UnknownJailException and prevent silent failures
- Added JailNotFoundError detection in jail_service.reload_all()
- Enhanced error handling in config_file_service to catch JailNotFoundError
- Added specific error message with logpath validation hints
- Added rollback test for this scenario
2. Task 2: Fix iptables-allports exit code 4 (xtables lock contention)
- Added global banaction setting in jail.conf with -w 5 lockingopt
- Removed redundant per-jail banaction overrides from bangui-sim and blocklist-import
- Added production compose documentation note
3. Task 3: Suppress log noise from unsupported backend/idle commands
- Implemented capability detection to cache command support status
- Double-check locking to minimize lock contention
- Avoids sending unsupported get <jail> backend/idle commands
- Returns default values without socket calls when unsupported
All changes include comprehensive tests and maintain backward compatibility.
