Copy-paste setup prompt

Set up tweet-factory on this machine for me.

Read these first, in order, and follow them:
1. https://docs.tweetfactory.sh/llms.txt
2. https://docs.tweetfactory.sh/agent.md
3. https://docs.tweetfactory.sh/install.md
4. https://docs.tweetfactory.sh/x-app.md

agent.md is the same runbook as SETUP.md in https://github.com/abhirupghosh/tweet-factory (plus this prompt). When a step and the repo disagree, trust the repo source and say so.

Rules:
- Install tf with the command in https://docs.tweetfactory.sh/install.md. Do not clone the repo unless the user already has a checkout or asked to develop from source.
- If a checkout is already on this machine, stay in it and use ./setup_x.sh. Do not delete it.
- Never invent credentials, tokens, or API keys. Never print secret values back to me.
- Write secrets only into .env. After writing, run chmod 600 .env. .tokens.json is created by tf auth and is already mode 0600.
- Do every step you can do yourself. Stop and ask me when a step says "Human required".
- After each step, run that step's verification check before continuing.
- tweet-factory writes drafts to files. It does not post to X. Do not post tweets for me.
- Run tf fetch on this machine only. The X refresh token rotates on every use; a second machine invalidates it.

Steps that need me (a human), which you cannot finish yourself:
- Creating an X developer app and copying the OAuth 2.0 Client ID and Client Secret.
- Clicking "Authorize app" in a browser during tf auth.
- Pasting any optional key I choose to provide (Tavily, Notion, Slack, or a direct LLM API key).

Start by installing tf (see the install page) and running `tf --help`. If you are already inside a checkout, run ./setup_x.sh --check instead and tell me what is missing.