feature(siril): make siril plugins work by exposing shared objects

modules/nixos/astro.nix

@@ -1,10 +1,27 @@
 { config, lib, pkgs, ... }:
 
+let
+  # Siril's Python plugins (sirilpy) run in a venv that pip-installs foreign
+  # manylinux wheels (numpy, GraXpert deps, ...). Those .so files need
+  # libstdc++ at runtime. nix-ld does NOT cover this: it only handles the
+  # initial exec of a foreign binary, but here a *native* nixpkgs python
+  # dlopen()s the foreign wheel. So we put the libs on LD_LIBRARY_PATH, which
+  # the python subprocess inherits from the Siril process.
+  sirilWithPlugins = pkgs.symlinkJoin {
+    name = "siril-with-plugins";
+    paths = [ pkgs.siril ];
+    nativeBuildInputs = [ pkgs.makeWrapper ];
+    postBuild = ''
+      wrapProgram $out/bin/siril \
+        --prefix LD_LIBRARY_PATH : ${lib.makeLibraryPath [ pkgs.stdenv.cc.cc.lib pkgs.zlib ]}
+    '';
+  };
+in
 {
   # install stellarium for target finding and siril for stacking
   environment.systemPackages = with pkgs; [
     stellarium
-    siril
+    sirilWithPlugins
   ];
 
   # StarNet++ has no nixpkgs package. Download the StarNet v2 ORT CLI build