Add Windows build script and update README with build instructions

a1_swap_mod_packer/paths.py

@@ -9,6 +9,16 @@ PATCH_CONFIG_FILE_NAME = "gcode_patches.ini"
 
 
 def program_root() -> Path:
+    compiled = globals().get("__compiled__")
+    if compiled is not None and getattr(compiled, "onefile", False):
+        containing_dir = getattr(compiled, "containing_dir", None)
+        if containing_dir:
+            return Path(containing_dir).resolve()
+
+        original_argv0 = getattr(compiled, "original_argv0", None)
+        if original_argv0:
+            return Path(original_argv0).resolve().parent
+
     if getattr(sys, "frozen", False):
         return Path(sys.executable).resolve().parent
     return Path(__file__).resolve().parents[1]