docs: describe Linear as optional task tracker (RM-1725 follow-up)

Merged
DE
1mo ago
+5-5

Summary

Follow-up to #204 per owner feedback: Linear is described as the tracker this repo's maintainers use — not a product requirement — across README.md, AGENTS.md, and CLAUDE.md. GitHub's role (source/PRs/reviews/checks/merge authority) is unchanged.

Linear: RM-1725

Link to Devin session: https://app.devin.ai/sessions/a140434abd7e47698540e8aea361a79a
Open in Devin Desktop: https://app.devin.ai/desktop/session/a140434abd7e47698540e8aea361a79a?variant=devin
Requested by: @rmems

Summary by cubic

Follows up on #204 to describe Linear as the task tracker this repo's maintainers use, not a required product dependency, in README.md, AGENTS.md, and CLAUDE.md. GitHub's role as source/PR/review/checks/merge authority is unchanged.