feat: add initial impl of efi-stub and kernel

build.zig

@@ -0,0 +1,35 @@
+const std = @import("std");
+const kernel_build = @import("kernel/build.zig");
+fn buildImage(b: *std.Build, target: std.Build.ResolvedTarget, optimize: std.builtin.OptimizeMode) *std.Build.Step {
+    switch (target.result.cpu.arch) {
+        .x86_64 => {
+            const arch_build = @import("arch/x86/boot/build.zig");
+            return arch_build.buildImage(b, optimize);
+        },
+        else => {
+            @panic("target architecture unsupported");
+        }
+    }
+
+}
+
+pub fn build(b: *std.Build) void {
+    const kernel_only_step = b.step("kernel", "Build the kernel only");
+    const full_step = b.step("full", "Build the full OS image");
+    const qemu_step = b.step("qemu", "Build and run in QEMU");
+    const target = b.resolveTargetQuery(.{
+        .cpu_arch = .x86_64,
+        .os_tag = .freestanding,
+        .abi = .none
+    });
+    const optimize = b.standardOptimizeOption(.{});
+    
+    const kernel_install = kernel_build.buildKernelBin(b, target, optimize);
+    kernel_only_step.dependOn(&kernel_install.step);
+    const image_step = buildImage(b, target, optimize);
+    b.getInstallStep().dependOn(image_step);
+    full_step.dependOn(image_step);
+
+    qemu_step.dependOn(image_step);
+    
+}