feat: add syntax highlighting for .ets files (#5889)

Author: nalin-singh

packages/opencode/src/lsp/language.ts

@@ -25,6 +25,7 @@ export const LANGUAGE_EXTENSIONS: Record<string, string> = {
   ".ex": "elixir",
   ".exs": "elixir",
   ".erl": "erlang",
+  ".ets": "typescript",
   ".hrl": "erlang",
   ".fs": "fsharp",
   ".fsi": "fsharp",