feat(nvim): setup for ipynb dev work

Setup:
- molten (run python code)
- otter (lsp in markdown codeblocks)
- jupytext (convert .ipynb files to .md files transparently)
- image (display images inside neovim (e.g. matplotlib graphs))

flake-modules/nvim.nix

@@ -1,22 +1,24 @@
 { inputs, ... }:
+let
+  standalone = ../nvim/standalone.nix;
+in
 {
   flake.overlays.nixvim = inputs.nixvim.overlays.default;
 
   perSystem =
     { pkgs, system, ... }:
-    let
-      nixvimLib = inputs.nixvim.lib.${system};
-      nixvim = inputs.nixvim.legacyPackages.${system};
-      module = {
+    {
+      # Check standalone nvim build
+      checks.nvim = inputs.nixvim.lib.${system}.check.mkTestDerivationFromNixvimModule {
         inherit pkgs;
         module = ../nvim/standalone.nix;
       };
-    in
-    {
-      # Check standalone nvim build
-      checks.nvim = nixvimLib.check.mkTestDerivationFromNixvimModule module;
 
       # Nvim standalone module
-      packages.nvim = nixvim.makeNixvimWithModule module;
+      packages.nvim = inputs.nixvim.legacyPackages.${system}.makeNixvimWithModule {
+        inherit pkgs;
+        module = standalone;
+      };
+
     };
 }

nvim/plugins.nix

@@ -5,7 +5,7 @@
   ...
 }:
 let
-  inherit (helpers) mkRaw enableExceptInTests;
+  inherit (helpers) mkRaw;
 in
 {
   config.plugins = {
@@ -160,7 +160,7 @@ in
       };
     };
     gitsigns.enable = true;
-    image.enable = enableExceptInTests;
+    image.enable = true;
     jupytext = {
       enable = true;
       settings.custom_language_formatting.python = {