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/ctdb/tdb.rs

@@ -1,7 +1,7 @@
 use std::collections::HashMap;
 use std::io::{self, Read, Write, Seek, SeekFrom};
 use std::path::Path;
-use std::sync::{Arc, Mutex, RwLock};
+use std::sync::{Mutex, RwLock};
 
 const TDB_MAGIC: u32 = 0x1BADFACE;
 const TDB_VERSION: u32 = 1;