Add exe packaging and install.bat

- esbuild bundle + @yao-pkg/pkg for standalone Windows exe
- install.bat copies to %LOCALAPPDATA%\kisync and adds to user PATH
- npm run package to build release/kisync.exe

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

.gitignore

@@ -1,4 +1,6 @@
 node_modules/
 dist/
+bundle/
+release/
 .kisync.json
 .kisync-state.json