feature/go-rewrite : base Go avec walk GUI

- Rewrite complet en Go : exe unique sans _internal/, sans extraction temp
- GUI Windows-native via github.com/lxn/walk (TableView, TextEdit, PushButton)
- Meme fonctionnalites : check repos, pull, checkout, auto-update, logs
- build.bat : go build -ldflags "-H windowsgui -s -w" -> 9.6 Mo, zero dependance

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

_internal/_tcl_data/encoding/iso2022-jp.enc

@@ -1,12 +0,0 @@
-# Encoding file: iso2022-jp, escape-driven
-E
-name		iso2022-jp
-init		{}
-final		{}
-ascii		\x1b(B
-jis0201		\x1b(J
-jis0208		\x1b$B
-jis0208		\x1b$@
-jis0212		\x1b$(D
-gb2312		\x1b$A
-ksc5601		\x1b$(C