Fix PyInstaller spec: bundle modules as Python code not raw data

Using datas to include modules/ caused stdlib imports (json etc.) to fail
at runtime. Adding modules/ to pathex lets PyInstaller properly analyse
and compile them into the bundle alongside the rest of the stdlib.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

es24n_conf.spec

@@ -1,15 +1,16 @@
 # PyInstaller spec for es24n_conf Windows .exe
 # Build with: pyinstaller es24n_conf.spec
 
+import os
 from PyInstaller.building.build_main import Analysis, PYZ, EXE
 
+modules_dir = os.path.join(os.path.dirname(os.path.abspath(SPEC)), "modules")
+
 a = Analysis(
     ["es24n_conf.py"],
-    pathex=[],
+    pathex=[modules_dir],
     binaries=[],
-    datas=[
+    datas=[],
-        ("modules", "modules"),
-    ],
     hiddenimports=[
         "serial",
         "serial.tools",
@@ -35,7 +36,7 @@ exe = EXE(
     bootloader_ignore_signals=False,
     strip=False,
     upx=True,
-    console=True,       # console app — must stay True for terminal UI
+    console=True,
     disable_windowed_traceback=False,
     target_arch=None,
     codesign_identity=None,