Agents: add role titles, reporting relationships, and an org-chart view

## Problem

As an owner builds a larger team of named agents, the Agents page shows who each agent is and which model it uses, but not what role the agent owns or how the team fits together. Names alone become difficult to scan once several agents are active.

For example, an owner may need to distinguish an Agentic Chief of Staff, Research and Intelligence Director, Technology and Automation Director, Editorial Director, and Health and Longevity Advisor. The owner also needs a simple way to see reporting and coordination relationships without maintaining a separate org chart outside Buzz.

## Proposed behavior

Add optional structured organization metadata to each managed agent:

- **Role title:** a short owner-defined title displayed beneath the agent name on the Agents page and in the agent profile.
- **Reports to:** an optional reference to another managed agent or to the human owner.
- **Team or division:** an optional owner-defined grouping for larger workforces.

Add two interchangeable views on the Agents page:

1. **Cards/list:** preserve the current view, with the role title visible and searchable.
2. **Org chart:** render the owner and agents as a collapsible hierarchy using the `reports to` relationships, with unassigned agents shown separately.

The org chart should support selecting an agent to open its existing profile or settings. Editing a title or reporting relationship should use the normal owner-only agent-management controls.

## Governance boundary

Organization metadata is descriptive, not authorization. Setting one agent to report to another must not grant channel access, tool access, credentials, approval authority, or permission to act. Those controls should remain explicit and separate.

Buzz should prevent or clearly flag circular reporting relationships and references to missing or archived agents. Team snapshots, workspace export/restore, and agent-configuration events should preserve the metadata where applicable.

## Acceptance criteria

- An owner can add, edit, and remove an optional role title for a managed agent.
- The title appears on the Agents page and agent profile without replacing the display name.
- An owner can set an optional `reports to` relationship and team/division.
- The Agents page can switch between the current card/list view and an org-chart view.
- The org chart handles multiple levels, unassigned agents, archived or missing managers, and circular-reference prevention.
- Search can find an agent by name or role title.
- Organization metadata survives restart and supported backup, snapshot, or export workflows.
- No permissions or authority change merely because organization metadata changes.

## Duplicate check

Searched issues and pull requests in `block/buzz` for `org chart`, `organizational chart`, `agent title`, `agent role`, `reporting line`, and `agent role hierarchy` on August 14, 2026. No direct issue or implementation was found.

Start at the existing Agents page, agent profile/settings, and owner-only agent-management controls; trace how agent configuration is persisted and how workspace export/restore handles it. Done means role titles, teams, reporting links, searchable cards/list and a safe collapsible org chart work without changing permissions, including missing or archived managers and circular-reference prevention.

Written by the indexing model from the issue text.