Fix TTY detection using /dev/tty instead of stdin fd

[ -t 0 ] checks whether stdin (fd 0) is a terminal, but git redirects
stdin to /dev/null for all hooks — so the check was always false, causing
the non-interactive warning to appear even in a normal terminal session.

The correct check is to attempt to open /dev/tty (the controlling terminal).
A terminal session always has an accessible /dev/tty even when stdin is
redirected; a GUI Git client has no controlling terminal at all, so the open
fails. This reliably distinguishes the two environments.

Author: albertodebortoli

post-checkout

@@ -129,8 +129,10 @@ log_info "Found $FOUND_SPEC, synchronizing tools..."
 
 # Check if Luca is installed and version is correct, install/update if not
 if ! is_luca_installed || ! is_luca_version_correct; then
-    if [ ! -t 0 ]; then
-        # No TTY — sudo cannot prompt for a password (e.g. GUI Git client).
+    if ! { true < /dev/tty; } 2>/dev/null; then
+        # No controlling terminal — sudo cannot prompt for a password (e.g. GUI Git client).
+        # Git always redirects stdin to /dev/null for hooks, so [ -t 0 ] is always false;
+        # opening /dev/tty is the reliable way to test for an accessible terminal session.
         # Skip the self-update and fall through to luca install below.
         if ! is_luca_installed; then
             log_warning "Non-interactive environment detected (e.g. GUI Git client). Luca is not installed — skipping automatic installation. Please run the setup from a terminal."