[Story] Author RFC-0001 (Cross-Cluster Identity)

[shreyanshjain7174]

Parent

Part of #146 (Cross-Cluster Agent Identity Federation epic).

Goal

Publish the design proposal for cross-cluster agent identity federation as a permanent RFC document in the repo.

Scope

• docs/rfcs/0001-cross-cluster-agent-identity.md authored
• docs/rfcs/README.md (RFC index + lifecycle)
• ROADMAP.md entry under "Exploring (RFC stage)"
• README.md linking RFC under Roadmap section
• GitHub Discussion opened in Ideas category, link added to RFC frontmatter
• Discussion link added to ROADMAP entry and this epic

Status

In progress. RFC merged on main; awaiting Discussion URL.

Acceptance

• RFC is discoverable from README and ROADMAP
• Discussion linked from RFC, ROADMAP, epic