Stand up OSS community: GitHub Discussions + good-first-issue triage

[db-tycoon-stephen]

Prepare the repo to receive external contributors:

• Enable GitHub Discussions; seed categories (Q&A, Ideas, Show & Tell).
• Triage the open backlog and tag genuinely-approachable items good first issue / help wanted.
• Add a short 'getting started as a contributor' pointer to the README.
• Define a lightweight triage cadence (label new issues, route bugs vs enhancements).

Owner: Karli (community/PM).

[db-tycoon-stephen]

Mirrored in Jira: PTC-26 (Epic: PTC-23 — QA & open-source community). Dev work continues here.