doom: replace Nix module with nix-ts-mode custom config

The new config is much smaller, the new mode uses native tree-sitter
integration, and appears to be actively developed. It does not have all
the features as the doom module, but I didn't seem to use any of it
anyway.

modules/emacs/doom/config.org

@@ -191,6 +191,17 @@ Tangle ~packages.el~ from within org-mode.
   :recipe (:type git :host github :repo "gleam-lang/gleam-mode"))
 
 (package! eat)
+
+(package! nix-ts-mode)
+
+(package! nix3
+  :recipe (:type git :host github :repo "emacs-twist/nix3.el"))
+
+(package! magit-nix3
+  :recipe (:type git
+           :host github
+           :repo "emacs-twist/nix3.el"
+           :files ("extra/magit-nix3.el")))
 #+end_src
 * Modus-themes
 Customize Modus-themes a little to make it more peppy and vibrant.
@@ -925,12 +936,17 @@ All the modifications that are necessary enough to exist, but not big enough to
 #+end_src
 
 ** Nix
-- Use ~nixpkgs-fmt~ for .nix file formatting
-  Nixpkgs PRs use this instead of ~nixfmt~ and gave me many a wondering annoyances on my PRs. So fudge it, I'm switching to it full-time.
 #+begin_src emacs-lisp :lexical t
-(use-package! nix-mode
-  :custom
-  (nix-nixfmt-bin "nixpkgs-fmt" "Path to nixfmt executable."))
+(after! tramp
+  (add-to-list 'tramp-remote-path "/run/current-system/sw/bin"))
+
+(use-package! nix-ts-mode
+  :mode "\\.nix\\'"
+  :init
+  ;; Treat flake.lock files as json
+  (add-to-list 'auto-mode-alist (cons "/flake\\.lock\\'" 'json-ts-mode))
+  :config
+  (add-hook 'nix-ts-mode-hook #'eglot-ensure'append))
 #+end_src
 
 ** EditorConfig
@@ -1102,7 +1118,7 @@ When Emacs is opened in Windows Subsystem for Linux, open web links in Firefox o
   ;; You can manually enable Combobulate with `M-x
   ;; combobulate-mode'.
   :after (treesit)
-  :hook ((nix-mode . combobulate-mode)
+  :hook ((nix-ts-mode . combobulate-mode)
          (python-ts-mode . combobulate-mode)
          (js-ts-mode . combobulate-mode)
          (css-ts-mode . combobulate-mode)

modules/emacs/doom/init.el

@@ -168,9 +168,9 @@
        lua               ; one-based indices? one-based indices
        ;;markdown          ; writing docs for people to ignore
        ;;nim               ; python + lisp at the speed of c
-       (nix                ; I hereby declare "nix geht mehr!"
-        +lsp
-        +tree-sitter)
+       ;;(nix                ; I hereby declare "nix geht mehr!"
+       ;; +lsp
+       ;; +tree-sitter)
        ;;ocaml             ; an objective camel
        (org                ; organize your plain life in plain text
         +babel             ; run inline code from org files