fix(neovim): prefer nvim-treesitter for C# folds

modules/home-manager/programs/neovim/lua/plugins/nvim-ufo.lua

@@ -0,0 +1,32 @@
+---@type LazySpec
+return {
+  "kevinhwang91/nvim-ufo",
+  opts = {
+    provider_selector = function(_, filetype, _)
+      ---@type table<string, UfoProviderEnum | UfoProviderEnum[]>
+      local ftDefaults = {
+        cs = "treesitter",
+      }
+
+      local function handleFallbackException(bufnr, err, providerName)
+        if type(err) == "string" and err:match("UfoFallbackException") then
+          return require("ufo").getFolds(bufnr, providerName)
+        else
+          return require("promise").reject(err)
+        end
+      end
+
+      return ftDefaults[filetype]
+          or function(bufnr)
+            return require("ufo")
+                .getFolds(bufnr, "lsp")
+                :catch(function(err)
+                  return handleFallbackException(bufnr, err, "treesitter")
+                end)
+                :catch(function(err)
+                  return handleFallbackException(bufnr, err, "indent")
+                end)
+          end
+    end,
+  },
+}