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/af.msg

@@ -1,49 +0,0 @@
-# created by tools/loadICU.tcl -- do not edit
-namespace eval ::tcl::clock {
-    ::msgcat::mcset af DAYS_OF_WEEK_ABBREV [list \
-        "So"\
-        "Ma"\
-        "Di"\
-        "Wo"\
-        "Do"\
-        "Vr"\
-        "Sa"]
-    ::msgcat::mcset af DAYS_OF_WEEK_FULL [list \
-        "Sondag"\
-        "Maandag"\
-        "Dinsdag"\
-        "Woensdag"\
-        "Donderdag"\
-        "Vrydag"\
-        "Saterdag"]
-    ::msgcat::mcset af MONTHS_ABBREV [list \
-        "Jan"\
-        "Feb"\
-        "Mar"\
-        "Apr"\
-        "Mei"\
-        "Jun"\
-        "Jul"\
-        "Aug"\
-        "Sep"\
-        "Okt"\
-        "Nov"\
-        "Des"\
-        ""]
-    ::msgcat::mcset af MONTHS_FULL [list \
-        "Januarie"\
-        "Februarie"\
-        "Maart"\
-        "April"\
-        "Mei"\
-        "Junie"\
-        "Julie"\
-        "Augustus"\
-        "September"\
-        "Oktober"\
-        "November"\
-        "Desember"\
-        ""]
-    ::msgcat::mcset af AM "VM"
-    ::msgcat::mcset af PM "NM"
-}