Apply clippy fixes for code quality

Clippy Fixes Applied:
- Removed unused imports
- Fixed manual implementation of .is_multiple_of()
- Fixed unnecessary_sort_by suggestions
- Added missing Ipv4Addr imports

Files Modified:
- forward_acl.rs: Add Ipv4Addr import
- known_hosts.rs: Add Ipv4Addr import
- Various files: Remove unused imports

Build: ✅ markbase-core
Tests: 495 passed

markbase-core/src/vfs/backup_scheduler.rs

@@ -269,7 +269,7 @@ impl BackupScheduler {
         
         let final_data = if self.config.compress != super::VfsCompression::None {
             let compressor = Compressor::new(VfsCompressionConfig {
-                algorithm: self.config.compress.clone(),
+                algorithm: self.config.compress,
                 min_size: 1024,
                 level: 3,
             });