After `yarn run build`, `git status` shows some Untracked files

Running `git add .` will add these files too, so we should ignore them. ``` $ git status On branch main Your branch is up to date with 'origin/main'. Untracked files: (use "git add <file>..." to include in what will be committed) agents/vanilla_agents/lib/array_agents/array_find_first_exists.d.ts agents/vanilla_agents/lib/array_agents/array_find_first_exists.js llm_agents/anthropic_agent/lib/utils.d.ts llm_agents/anthropic_agent/lib/utils.js llm_agents/tools_agent/lib/tools_agent-sequential.d.ts llm_agents/tools_agent/lib/tools_agent-sequential.js nothing added to commit but untracked files present (use "git add" to track) ```