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/encrypted_fs.rs

@@ -16,8 +16,7 @@ use aes_gcm::{
 };
 use sha2::{Sha256, Digest};
 
-use super::{VfsBackend, VfsFile, VfsStat, VfsError, VfsDirEntry};
-use super::open_flags::OpenFlags;
+use super::{VfsBackend, VfsFile, VfsStat, VfsError};
 use super::local_fs::LocalFs;
 
 const ENCRYPTED_MAGIC: &[u8] = b"MBE1";  // MarkBase Encrypted v1
@@ -62,7 +61,7 @@ impl EncryptedVfs {
         Self { inner, config }
     }
 
-    pub fn wrap_local_fs(root: PathBuf, config: EncryptedVfsConfig) -> Self {
+    pub fn wrap_local_fs(_root: PathBuf, config: EncryptedVfsConfig) -> Self {
         Self::new(Box::new(LocalFs::new()), config)
     }
 
@@ -132,8 +131,8 @@ fn rand_key(len: usize) -> Vec<u8> {
     use std::time::{SystemTime, UNIX_EPOCH};
     let now = SystemTime::now().duration_since(UNIX_EPOCH).unwrap().as_nanos();
     let mut hasher = Sha256::new();
-    hasher.update(&now.to_le_bytes());
-    hasher.update(&[0u8; 32]);
+    hasher.update(now.to_le_bytes());
+    hasher.update([0u8; 32]);
     let hash = hasher.finalize();
     hash[..len].to_vec()
 }