fix: add Mesa EGL software rendering for Linux environments without GPU

flake.nix

@@ -41,7 +41,12 @@
             pkgs.gdk-pixbuf
             pkgs.libsoup_3
             pkgs.webkitgtk_4_1
-          ] ++ (if pkgs.stdenv.isDarwin then [
+          ] ++ (if pkgs.stdenv.isLinux then [
+            # Mesa with software rendering support for environments without a GPU
+            # (e.g., VMs, CI, containers). Provides libEGL_mesa.so and swrast DRI
+            # drivers needed by WebKitGTK to initialize EGL.
+            pkgs.mesa
+          ] else []) ++ (if pkgs.stdenv.isDarwin then [
             # macOS-specific dependencies
             pkgs.darwin.apple_sdk.frameworks.WebKit
             pkgs.darwin.apple_sdk.frameworks.AppKit
@@ -51,6 +56,15 @@
           shellHook = ''
             echo "Using Rust version: $(rustc --version)"
             echo "Tauri development environment ready"
+          ''
+          # On Linux, configure Mesa EGL for software rendering so WebKitGTK works
+          # in environments without a GPU (VMs, containers, headless servers).
+          + pkgs.lib.optionalString pkgs.stdenv.isLinux ''
+            export __EGL_VENDOR_LIBRARY_FILENAMES=${pkgs.mesa}/share/glvnd/egl_vendor.d/50_mesa.json
+            export LIBGL_DRIVERS_PATH=${pkgs.mesa}/lib/dri
+            export LIBGL_ALWAYS_SOFTWARE=1
+            export WEBKIT_DISABLE_COMPOSITING_MODE=1
+            export WEBKIT_DISABLE_DMABUF_RENDERER=1
           '';
         };
       }