Fix cdef size_t size on Win64 (LLP64), require 64-bit builds

The generated cdef typedef'd size_t as unsigned long: 8 bytes on LP64
but only 4 on 64-bit Windows, where C's size_t is 8. cffi's import-time
struct layout verification then failed (aegis_raf_scratch.len: cdef
says 4, C compiler says 8). cffi pre-defines size_t/uint8_t with the
correct platform sizes, so don't typedef them.

Also hard-fail 32-bit build attempts in setup.py; 32-bit platforms are
no longer supported.

setup.py

@@ -9,6 +9,11 @@ from setuptools import setup
 
 ROOT = Path(__file__).parent.resolve()
 
+if sys.maxsize <= 2**32:
+    raise RuntimeError(
+        "aeg does not support 32-bit platforms; build with a 64-bit Python"
+    )
+
 libaegis_static = ROOT / "libaegis/zig-out/lib" / (
     "aegis.lib" if sys.platform == "win32" else "libaegis.a"
 )

src/aeg/aegis_cdef.h

@@ -1,8 +1,5 @@
 /* This file is generated with tools/generate.py. Do not edit. */
 
-typedef unsigned char uint8_t;
-typedef unsigned long size_t;
-
 /* aegis.h */
 int aegis_init(void);
 int aegis_verify_16(const uint8_t *x, const uint8_t *y);

tools/generate.py

@@ -74,12 +74,12 @@ def format_declaration(decl: str, max_width: int = 100) -> str:
 
 
 def generate_cdef(include_dir: pathlib.Path) -> str:
+    # cffi pre-defines uint8_t, size_t, etc. with the correct platform sizes.
+    # Do not typedef them here: "unsigned long" matches size_t on LP64 but is
+    # 4 bytes vs 8 on Win64 (LLP64), breaking struct layout verification.
     lines = [
         "/* This file is generated with tools/generate.py. Do not edit. */",
         "",
-        "typedef unsigned char uint8_t;",
-        "typedef unsigned long size_t;",
-        "",
     ]
 
     headers = [