Refactor entire codebase and rewrite documentation

Tests/DataLiteCoreTests/Structures/SQLiteErrorTests.swift

@@ -0,0 +1,28 @@
+import Foundation
+import Testing
+import DataLiteC
+@testable import DataLiteCore
+
+struct SQLiteErrorTests {
+    @Test func testInitWithConnection() {
+        var db: OpaquePointer? = nil
+        defer { sqlite3_close(db) }
+        sqlite3_open(":memory:", &db)
+        sqlite3_exec(db, "INVALID SQL", nil, nil, nil)
+        
+        let error = SQLiteError(db!)
+        #expect(error.code == SQLITE_ERROR)
+        #expect(error.message == "near \"INVALID\": syntax error")
+    }
+    
+    @Test func testInitWithCodeAndMessage() {
+        let error = SQLiteError(code: 1, message: "Test Error Message")
+        #expect(error.code == 1)
+        #expect(error.message == "Test Error Message")
+    }
+    
+    @Test func testDescription() {
+        let error = SQLiteError(code: 1, message: "Test Error Message")
+        #expect(error.description == "SQLiteError code: 1 message: Test Error Message")
+    }
+}