Removed unused parts of Godot for export

nix/package.nix

@@ -23,6 +23,10 @@ let
   # disable SIMD on some CPUs (e.g. Firefox on x86/x64 without SSE4.1) and then
   # reject the module with "v128 not enabled", so compile a matching template
   # without it and ship that instead.
+  #
+  # The template is also stripped down to what this 2D game needs: no 3D, 3D
+  # physics, navigation, XR or any engine module it never touches. 2D physics is
+  # kept because `scenes/units/unit.tscn` uses an `Area2D` for unit hover.
   webTemplates = stdenv.mkDerivation (finalAttrs: {
     pname = "godot-web-nosimd-template";
     inherit (godot_4_6) version;
@@ -54,8 +58,25 @@ let
       # archive the template) rejects because it predates 1980.
       find . -exec touch -h {} +
 
+      # Only the modules this game actually uses are compiled in; everything
+      # else (3D and its importers, compressed/extra image formats, audio
+      # codecs, ENet/WebRTC/UPnP, regex, SVG rasterisation, texture
+      # compressors, ...) is left out. `modules_enabled_by_default=no` keeps a
+      # future upstream module out of the build until it is enabled here.
+      #
+      # `force_png` (project.godot) makes the importer store lossless textures
+      # as PNG, so the WebP module is not needed at runtime.
       scons platform=web target=template_release \
         wasm_simd=no threads=no dlink_enabled=no \
+        disable_3d=yes disable_physics_3d=yes \
+        disable_navigation_2d=yes disable_navigation_3d=yes disable_xr=yes \
+        modules_enabled_by_default=no \
+        module_freetype_enabled=yes \
+        module_gdscript_enabled=yes \
+        module_multiplayer_enabled=yes \
+        module_noise_enabled=yes \
+        module_text_server_adv_enabled=yes \
+        module_websocket_enabled=yes \
         -j$NIX_BUILD_CORES
 
       runHook postBuild