rename types.h to intdef.h and replace types.h with a symlink.

`intdef.h` is more clear in the purpose that it describes, rather than
`types`, `types` is too generic.
Note: floating points are still defined in this header, I imagine this
to be removed later, alongside the compatibility symlink.

src/util/intdef.h

@@ -0,0 +1,24 @@
+// Copyright (c) 2025 Quinn
+// Licensed under the MIT Licence. See LICENSE for details
+#pragma once
+
+/* variable-width integer types */
+typedef unsigned int uint;         // ≥16 bit unsigned integer
+typedef unsigned long ulong;       // ≥32 bit unsigned integer
+typedef signed long long llong;    // ≥64 bit signed integer
+typedef unsigned long long ullong; // ≥64 bit unsigned integer
+
+/* fixed-width integer types */
+#include <stdint.h>
+typedef int8_t i8;
+typedef int16_t i16;
+typedef int32_t i32;
+typedef int64_t i64;
+typedef uint8_t u8;
+typedef uint16_t u16;
+typedef uint32_t u32;
+typedef uint64_t u64;
+
+/* floating point types */
+typedef float f32;  // single-precision floating-point
+typedef double f64; // double-precision floating-point