fix(linux): ship gio-launch-desktop so the bundled libgio can launch URLs

Root cause of the broken 'Sign in with Plex' and update links on
portable builds: the bundle ships Ubuntu's libgio, whose compiled-in
helper path (/usr/lib/x86_64-linux-gnu/glib-2.0/gio-launch-desktop)
exists only on Debian-family hosts. glib then falls back to a bare PATH
search, and distros like Fedora keep the helper in /usr/libexec outside
PATH, so every URL/desktop-file spawn failed. Installing the RPM masked
it only because system glib is built with the right path.

Bundle the build host's gio-launch-desktop next to the libgio it was
built with (bundle-libs.sh now fails the build if libgio is bundled and
the helper cannot be found) and export GIO_LAUNCH_DESKTOP from plezy.sh,
which glib checks before its compiled-in path. Covers the tarball and
the deb/rpm/pacman packages alike, since they all ship the same bundle
and launch through the wrapper.

close #1477

linux/packaging/bundle-libs.sh

@@ -114,6 +114,34 @@ if [[ -n "$GIO_MODULE_DIR" && -d "$GIO_MODULE_DIR" ]]; then
     bundle_module_dir "$GIO_MODULE_DIR" "$GIO_DEST"
 fi
 
+# gio-launch-desktop helper
+# libgio spawns URI/desktop-file handlers through this binary. Its location is
+# compiled into libgio as the *build host's* pkglibexecdir (an Ubuntu
+# multiarch path), which does not exist on other distros, and glib's bare-name
+# PATH fallback misses hosts that keep the helper in /usr/libexec (Fedora).
+# Every launchUrl then failed (#1477). Ship the helper that matches the
+# bundled libgio; plezy.sh points GIO_LAUNCH_DESKTOP at it.
+if compgen -G "$LIB_DIR/libgio-2.0.so*" > /dev/null; then
+    GLIB_LIBDIR="$(pkg-config --variable=libdir glib-2.0 2>/dev/null || true)"
+    GIO_HELPER=""
+    for candidate in "${GLIB_LIBDIR:+$GLIB_LIBDIR/glib-2.0/gio-launch-desktop}" \
+        /usr/libexec/gio-launch-desktop \
+        /usr/lib/glib-2.0/gio-launch-desktop; do
+        if [[ -n "$candidate" && -x "$candidate" ]]; then
+            GIO_HELPER="$candidate"
+            break
+        fi
+    done
+    if [[ -z "$GIO_HELPER" ]]; then
+        echo "Error: libgio is bundled but no gio-launch-desktop helper was found on the build host." >&2
+        echo "Without it, URL launching breaks on every distro whose glib layout differs from the builder's." >&2
+        exit 1
+    fi
+    mkdir -p "$LIB_DIR/glib-2.0"
+    cp -a "$GIO_HELPER" "$LIB_DIR/glib-2.0/gio-launch-desktop"
+    echo "==> Bundled gio-launch-desktop from $GIO_HELPER"
+fi
+
 # GTK IM modules + print backends
 GTK_LIBDIR="$(pkg-config --variable=libdir gtk+-3.0 2>/dev/null || true)"
 if [[ -n "$GTK_LIBDIR" ]]; then

linux/packaging/plezy.sh

@@ -27,6 +27,14 @@ if [[ -d "$INSTALL_DIR/lib/gio/modules" ]]; then
     export GIO_MODULE_DIR="$INSTALL_DIR/lib/gio/modules"
 fi
 
+# gio-launch-desktop: the bundled libgio spawns URL/desktop-file handlers
+# through this helper. Its compiled-in path only exists on the build distro
+# and glib's PATH fallback misses hosts that keep it in /usr/libexec, which
+# broke every URL launch (#1477). Point libgio at the bundled copy.
+if [[ -x "$INSTALL_DIR/lib/glib-2.0/gio-launch-desktop" ]]; then
+    export GIO_LAUNCH_DESKTOP="$INSTALL_DIR/lib/glib-2.0/gio-launch-desktop"
+fi
+
 # GTK IM modules
 if [[ -f "$INSTALL_DIR/lib/gtk-3.0/3.0.0/immodules.cache" ]]; then
     export GTK_IM_MODULE_FILE="$INSTALL_DIR/lib/gtk-3.0/3.0.0/immodules.cache"