docs: add Xquik Streamlit source

[kriptoburak]

Summary

• document an optional server-side Xquik source for fresh X/Twitter analytics data
• fix the README clone command to point at the current repository
• replace the broken virtualenv activation path with a working venv/bin/activate flow

Improvements

1. Xquik integration readiness: explains how to keep XQUIK_API_KEY outside the repo and export posts into the existing Streamlit and notebook data flow.
2. Target repo setup fixes: corrects the clone URL and virtual environment commands so the documented local setup works from a fresh checkout.

Validation

• git diff --check
• python3 -m compileall -q app

Notes

• The repository includes an MIT license file, and this change is limited to README setup guidance.