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/opt0.4/pkgIndex.tcl

@@ -1,12 +0,0 @@
-# Tcl package index file, version 1.1
-# This file is generated by the "pkg_mkIndex -direct" command
-# and sourced either when an application starts up or
-# by a "package unknown" script.  It invokes the
-# "package ifneeded" command to set up package-related
-# information so that packages will be loaded automatically
-# in response to "package require" commands.  When this
-# script is sourced, the variable $dir must contain the
-# full path name of this file's directory.
-
-if {![package vsatisfies [package provide Tcl] 8.5-]} {return}
-package ifneeded opt 0.4.9 [list source -encoding utf-8 [file join $dir optparse.tcl]]