Refactor entire codebase and rewrite documentation

Sources/DataLiteCore/Classes/Connection+Key.swift

@@ -1,41 +1,39 @@
 import Foundation
 
 extension Connection {
-    /// An encryption key for accessing an encrypted SQLite database.
+    /// An encryption key for opening an encrypted SQLite database.
     ///
-    /// Used after the connection is opened to unlock the contents of the database.
-    /// Two formats are supported: a passphrase with subsequent derivation, and
-    /// a raw 256-bit key (32 bytes) without transformation.
+    /// The key is applied after the connection is established to unlock the database contents.
+    /// Two formats are supported:
+    /// - a passphrase, which undergoes key derivation;
+    /// - a raw 256-bit key (32 bytes) passed without transformation.
     public enum Key {
-        /// A passphrase used to derive an encryption key.
+        /// A human-readable passphrase used for key derivation.
         ///
-        /// Intended for human-readable strings such as passwords or PIN codes.
-        /// The string is passed directly without escaping or quoting.
+        /// The passphrase is supplied as-is and processed by the underlying key derivation
+        /// mechanism configured in the database engine.
         case passphrase(String)
         
         /// A raw 256-bit encryption key (32 bytes).
         ///
-        /// No key derivation is performed. The key is passed as-is and must be
-        /// securely generated and stored.
+        /// The key is passed directly to the database without derivation. It must be securely
+        /// generated and stored.
         case rawKey(Data)
         
-        /// The string value to be passed to the database engine.
+        /// The string value passed to the database engine.
         ///
-        /// For `.passphrase`, this is the raw string exactly as provided.
-        /// For `.rawKey`, this is a hexadecimal literal in the format `X'...'`.
+        /// For `.passphrase`, returns the passphrase exactly as provided.
+        /// For `.rawKey`, returns a hexadecimal literal in the format `X'...'`.
         public var keyValue: String {
             switch self {
             case .passphrase(let string):
-                return string
+                string
             case .rawKey(let data):
-                return data.sqliteLiteral
+                data.sqliteLiteral
             }
         }
         
-        /// The length of the key value in bytes.
-        ///
-        /// Returns the number of bytes in the UTF-8 encoding of `keyValue`,
-        /// not the length of the original key or string.
+        /// The number of bytes in the string representation of the key.
         public var length: Int32 {
             Int32(keyValue.utf8.count)
         }