Define conversation subjects, projects/tasks, and repositories/branches

[baxen]

Summary

• Define Conversation Subjects (NIP-CS): canonical channel/thread relationships, exclusive/primary/attachment claims, tags, identity, revisions, and authorization.
• Define Projects and Tasks (NIP-PT) independently of repositories.
• Define Repositories and Branches (NIP-RB), mapping Buzz repository identities to NIP-34 coordinates and branches to Buzz repositories plus Git refs.
• Add core domain types and structural validation for subject declarations, repository coordinates, and branch refs.

Scope

This draft contains protocol specifications and the initial core types. It does not enable new relay event kinds or implement transactional acceptance, storage projections, or query/subscription integration. The Rust types still need alignment with the detailed specifications. No frontend changes.

Design choices for review

• Exclusive claims exclude all other subjects; primary claims allow attachments.
• Controller-signed revisions use prev for optimistic concurrency.
• Conversation homes are immutable.
• Primary/exclusive claims require channel administration.
• Branch retirement is terminal.

Verification

• cargo check -p buzz-core passed.
• Formatting and git diff --check passed.
• Push scope, organization, branch-skew, LFS, and file-size checks passed.
• Broad Rust and desktop pre-push test lanes were skipped with approval; no completed test-suite result is claimed.

[github-actions]

🔐 Codex Security Review

Status: review required for the current range.

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