Import live-streamer gold

[ukimsanov]

Summary

• Import the tracked contents from live-streamer-gold into heygen-com/live-streamer while preserving the existing repo hygiene files (LICENSE, CONTRIBUTING.md, and GitHub Actions CI).
• Add the expanded showrunner, stream orchestrator, chat ingester, script producer, scripts, docs, research notes, tests, and operational runbooks from the gold checkout.
• Scrub public-unfriendly local details before publishing: no .env files, browser profile, local state/logs, virtualenvs, caches, real-looking token placeholders, personal /Users/... paths, or personal sample repo names.
• Harden .gitignore for assistant-local metadata (.codex/, .claude/) and keep runtime/cache artifacts ignored.

Validation

• Secret/local artifact scans: no .env, credential/key files, browser-profile/state/log/cache dirs, files over 1 MB, or real-looking token/webhook matches in the committed tree.
• git diff --check
• cd chat_ingester && uv run pytest -q -> 114 passed
• cd script_producer && uv run pytest -q -> 55 passed
• cd showrunner && uv run pytest -q -> 1377 passed, 7 deselected
• cd stream_orchestrator && uv run pytest -q -> 228 passed