Added tons of opcode documentation, changed license to ISC and a lot of file refactoring.

src/vm/arrays/contains.c

@@ -1,3 +1,36 @@
+/**
+ * This file is part of the Fun programming language.
+ * https://hanez.org/project/fun/
+ *
+ * Copyright 2025 Johannes Findeisen <you@hanez.org>
+ * Licensed under the terms of the ISC license.
+ * https://opensource.org/license/isc-license-txt
+ */
+
+/**
+* @file contains.c
+ * @brief Implements the OP_CONTAINS opcode for checking array membership in the VM.
+ *
+ * This file handles the OP_CONTAINS instruction, which checks if a value is present in an array.
+ * The value and array are popped from the stack, and a boolean result (1/0) is pushed back.
+ *
+ * Behavior:
+ * - Pops the value and array from the stack.
+ * - Checks if the value is present in the array.
+ * - Pushes 1 (true) or 0 (false) onto the stack.
+ *
+ * Error Handling:
+ * - Exits with an error if the array is of the wrong type.
+ *
+ * Example:
+ * // Bytecode: OP_CONTAINS
+ * // Stack before: [20, [10, 20, 30]]
+ * // Stack after: [1]
+ *
+ * @author Johannes Findeisen
+ * @date 2025-10-16
+ */
+
 case OP_CONTAINS: {
     Value needle = pop_value(vm);
     Value arr = pop_value(vm);