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/msgs/gl.msg

@@ -1,47 +0,0 @@
-# created by tools/loadICU.tcl -- do not edit
-namespace eval ::tcl::clock {
-    ::msgcat::mcset gl DAYS_OF_WEEK_ABBREV [list \
-        "Dom"\
-        "Lun"\
-        "Mar"\
-        "M\u00e9r"\
-        "Xov"\
-        "Ven"\
-        "S\u00e1b"]
-    ::msgcat::mcset gl DAYS_OF_WEEK_FULL [list \
-        "Domingo"\
-        "Luns"\
-        "Martes"\
-        "M\u00e9rcores"\
-        "Xoves"\
-        "Venres"\
-        "S\u00e1bado"]
-    ::msgcat::mcset gl MONTHS_ABBREV [list \
-        "Xan"\
-        "Feb"\
-        "Mar"\
-        "Abr"\
-        "Mai"\
-        "Xu\u00f1"\
-        "Xul"\
-        "Ago"\
-        "Set"\
-        "Out"\
-        "Nov"\
-        "Dec"\
-        ""]
-    ::msgcat::mcset gl MONTHS_FULL [list \
-        "Xaneiro"\
-        "Febreiro"\
-        "Marzo"\
-        "Abril"\
-        "Maio"\
-        "Xu\u00f1o"\
-        "Xullo"\
-        "Agosto"\
-        "Setembro"\
-        "Outubro"\
-        "Novembro"\
-        "Decembro"\
-        ""]
-}