Migrate updater LAN and devkit features from old repo

devkit/build_server.bat

@@ -0,0 +1,24 @@
+@echo off
+REM ── JE-Skin DevKit: 打包 Python gRPC server 为 exe ──
+REM 前提: pip install pyinstaller grpcio grpcio-tools openpyxl
+
+echo [1/3] Generating gRPC stubs...
+python -m grpc_tools.protoc ^
+  -I../src-tauri/proto ^
+  --python_out=. ^
+  --grpc_python_out=. ^
+  ../src-tauri/proto/sensor_stream.proto
+
+echo [2/3] Building exe with PyInstaller...
+pyinstaller ^
+  --onefile ^
+  --name je-skin-devkit-server ^
+  --add-data "sensor_stream_pb2*.py;." ^
+  --hidden-import grpc ^
+  --hidden-import openpyxl ^
+  --noconfirm ^
+  sensor_server.py
+
+echo [3/3] Done!
+echo Output: dist/je-skin-devkit-server.exe
+pause