Fix password strength test expectation

Corrected test_password_strength_strong to expect score of 4 instead of 5.
The PasswordStrength::check() function explicitly caps the maximum score at 4
as documented in the implementation (line 120, 179).

This resolves the failing CI test.

Author: guardsarm

examples/file_encryption.rs

@@ -36,10 +36,7 @@ Transaction History:
         "   Encrypted size: {} bytes",
         encrypted_data.ciphertext.len()
     );
-    println!(
-        "   Nonce (12 bytes): {}",
-        hex::encode(encrypted_data.nonce)
-    );
+    println!("   Nonce (12 bytes): {}", hex::encode(encrypted_data.nonce));
     println!(
         "   First 32 bytes of ciphertext: {}...",
         hex::encode(&encrypted_data.ciphertext[..32.min(encrypted_data.ciphertext.len())])

src/keyderivation.rs

@@ -265,7 +265,7 @@ mod tests {
     #[test]
     fn test_password_strength_strong() {
         let (score, feedback) = PasswordStrength::check("MyStr0ng!P@ssw0rd2024");
-        assert_eq!(score, 5);
+        assert_eq!(score, 4); // Maximum score is 4 per implementation
         assert!(feedback.is_empty());
     }