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/mt.msg

@@ -1,27 +0,0 @@
-# created by tools/loadICU.tcl -- do not edit
-namespace eval ::tcl::clock {
-    ::msgcat::mcset mt DAYS_OF_WEEK_ABBREV [list \
-        "\u0126ad"\
-        "Tne"\
-        "Tli"\
-        "Erb"\
-        "\u0126am"\
-        "\u0120im"]
-    ::msgcat::mcset mt MONTHS_ABBREV [list \
-        "Jan"\
-        "Fra"\
-        "Mar"\
-        "Apr"\
-        "Mej"\
-        "\u0120un"\
-        "Lul"\
-        "Awi"\
-        "Set"\
-        "Ott"\
-        "Nov"]
-    ::msgcat::mcset mt BCE "QK"
-    ::msgcat::mcset mt CE ""
-    ::msgcat::mcset mt DATE_FORMAT "%A, %e ta %B, %Y"
-    ::msgcat::mcset mt TIME_FORMAT_12 "%l:%M:%S %P"
-    ::msgcat::mcset mt DATE_TIME_FORMAT "%A, %e ta %B, %Y %l:%M:%S %P %z"
-}