feat(agents): publish structured work reports

[contentscoin]

Summary

• teach managed agents when to publish or update a signed work-report
• keep progress and small conversational replies on ordinary messages
• restrict canonical multi-agent reports to explicitly named coordinators
• recognize buzz messages report as a human-visible publish in the reply guard

Behavior

The base prompt now distinguishes representative outcomes from progress logs. It documents strict status meanings, prior-based updates, scaled fields, callback notifications, and the no-self-election rule for multi-agent coordinators.

This PR is stacked on #7057, which introduces the buzz messages report CLI and protocol. Review scope is the single top commit 5f46ec65f touching three agent-facing files.

Validation

• cargo fmt --all -- --check passes
• git diff --check passes
• local package compilation is blocked before project code by missing Windows linkers (link.exe; gnullvm fallback also lacks x86_64-w64-mingw32-clang)
• fork CI is the full compile/test gate

Follow-up boundary

This does not auto-summarize worker messages or infer a coordinator. Those behaviors require an explicit workflow/assignment authority model and are intentionally excluded.

[github-actions]

🔐 Codex Security Review

Status: review required for the current range.

The current range is eed74bde2f4797714335ac10c56c0b0244c1def4...48b98a6cd3f4702fba914c3bf1470d922c989dee.
A new review must complete for this exact range. When manual authorization
is required, a Block organization member must comment exactly
@buzz-security-review 48b98a6cd3f4702fba914c3bf1470d922c989dee to authorize a new review.
Any previous review applies only to its recorded range.

[contentscoin]

Maintainer review requested. Fork CI run 33341022981 completed successfully at head 5f46ec6 across Rust fmt/clippy/unit, Windows Rust, both musl targets, Desktop Core/macOS/Smoke/Integration E2E, relay/backend E2E, and security. Fresh-frame review found no blockers: structured reports remain opt-in for substantive terminal/review states, ordinary progress stays in messages, canonical multi-agent reporting requires an explicitly named coordinator, and the reply guard recognizes reports as human-visible publishes. This PR is stacked on #7057 and should merge after it.

[contentscoin]

Review follow-up at 48b98a6cd: aligned the introductory status tokens with the CLI's kebab-case spellings (in-review, needs-decision) and made the coordinator prompt-contract assertion whitespace-insensitive. No behavioral scope changed. Fork CI run 33342462661 is the final gate.

[contentscoin]

Closing this upstream contribution because the deployment target was clarified as contentscoin/buzz. The combined, fully validated change was merged as contentscoin#6 (merge commit 5bbf0b6).