Revert "Remove treemacs"

This reverts commit 090d9fde94.

home-manager/software/emacs/default.nix

@@ -79,6 +79,8 @@
       epkgs.string-inflection
       epkgs.swiper
       epkgs.system-packages
+      epkgs.treemacs
+      epkgs.treemacs-evil
       epkgs.use-package
       epkgs.use-package-ensure-system-package
       epkgs.vterm

home-manager/software/emacs/emacs.d/lib/languageserver.el

@@ -7,6 +7,8 @@
          (ansible . lsp)
          ;; if you want which-key integration
          (lsp-mode . lsp-enable-which-key-integration))
+  :config
+  (lsp-treemacs-sync-mode 1)
   :commands lsp)
 
 ;; optionally

home-manager/software/emacs/emacs.d/lib/treemacs.el

@@ -0,0 +1,6 @@
+(use-package treemacs
+  :bind ("<f12>" . treemacs)
+  :config
+  (progn
+    (use-package treemacs-evil
+      :demand t)))

home-manager/software/emacs/emacs.d/modules.el

@@ -44,5 +44,6 @@
 (load-file (modules-path "keyring_update.el"))
 (load-file (modules-path "manuals.el"))
 (load-file (modules-path "mu4e.el"))
+(load-file (modules-path "treemacs.el"))
 (load-file (modules-path "vterm.el"))
 (load-file (modules-path "yasnippet.el"))