Update README.md, docs/api/README.md, session-lifecycle guide,
webhooks-and-events guide, and archive docs (BOT_INTEGRATION,
API_QUICK_REFERENCE) with new endpoints and vote.received event.
Made-with: Cursor
Moved 9 documentation .md files from root into docs/.
Moved 4 test scripts from root into tests/.
Updated cross-references in README.md and docs to reflect new paths.
Co-authored-by: Cursor <cursoragent@cursor.com>
