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/it.msg

@@ -1,54 +0,0 @@
-# created by tools/loadICU.tcl -- do not edit
-namespace eval ::tcl::clock {
-    ::msgcat::mcset it DAYS_OF_WEEK_ABBREV [list \
-        "dom"\
-        "lun"\
-        "mar"\
-        "mer"\
-        "gio"\
-        "ven"\
-        "sab"]
-    ::msgcat::mcset it DAYS_OF_WEEK_FULL [list \
-        "domenica"\
-        "luned\u00ec"\
-        "marted\u00ec"\
-        "mercoled\u00ec"\
-        "gioved\u00ec"\
-        "venerd\u00ec"\
-        "sabato"]
-    ::msgcat::mcset it MONTHS_ABBREV [list \
-        "gen"\
-        "feb"\
-        "mar"\
-        "apr"\
-        "mag"\
-        "giu"\
-        "lug"\
-        "ago"\
-        "set"\
-        "ott"\
-        "nov"\
-        "dic"\
-        ""]
-    ::msgcat::mcset it MONTHS_FULL [list \
-        "gennaio"\
-        "febbraio"\
-        "marzo"\
-        "aprile"\
-        "maggio"\
-        "giugno"\
-        "luglio"\
-        "agosto"\
-        "settembre"\
-        "ottobre"\
-        "novembre"\
-        "dicembre"\
-        ""]
-    ::msgcat::mcset it BCE "aC"
-    ::msgcat::mcset it CE "dC"
-    ::msgcat::mcset it AM "m."
-    ::msgcat::mcset it PM "p."
-    ::msgcat::mcset it DATE_FORMAT "%d %B %Y"
-    ::msgcat::mcset it TIME_FORMAT "%H:%M:%S"
-    ::msgcat::mcset it DATE_TIME_FORMAT "%d %B %Y %H:%M:%S %z"
-}