fix: CI don't replace live binary, pass build path to ISO script

Remove the cp to /usr/local/bin that caused 'Text file busy'.
The ISO build script now accepts ARCHIPELAGO_BIN env var to find
the freshly built binary instead of requiring it installed.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

image-recipe/build-auto-installer-iso.sh

@@ -508,9 +508,10 @@ fi
 # Try to get from live server first (unless BUILD_FROM_SOURCE=1)
 BACKEND_CAPTURED=0
 if [ "$BUILD_FROM_SOURCE" != "1" ]; then
-    # Direct copy from local filesystem (when running on target with sudo)
-    if [ -f "/usr/local/bin/archipelago" ]; then
-        cp "/usr/local/bin/archipelago" "$ARCH_DIR/bin/archipelago"
+    # Direct copy from ARCHIPELAGO_BIN env, local install, or remote
+    local BIN="${ARCHIPELAGO_BIN:-/usr/local/bin/archipelago}"
+    if [ -f "$BIN" ]; then
+        cp "$BIN" "$ARCH_DIR/bin/archipelago"
         chmod +x "$ARCH_DIR/bin/archipelago"
         echo "   ✅ Backend captured from local system ($(du -h "$ARCH_DIR/bin/archipelago" | cut -f1))"
         BACKEND_CAPTURED=1