nvim: some isabelle niceties

.config/nvim/lua/_lazy.lua

@@ -89,6 +89,7 @@ local plugins = {
         version = "^3",
         lazy = false,
     },
+    "Treeniks/isabelle-syn.nvim",
     {
         "turbio/bracey.vim",
         build = "npm install --prefix server",

.config/nvim/lua/cmds.lua

@@ -12,6 +12,7 @@ vim.filetype.add {
         sk = "skel",
         skel = "skel",
         typ = "typst",
+        thy = "isabelle",
     },
 }