v2.4.0 — Roster Control 🎛️

Added

• update_agent MCP tool — change a roster agent's model, tools, system_prompt, name, description or department without raw SQL or the dashboard; omitted fields stay unchanged, null clears the nullable ones, and the reply names the Task-tool tier the new model routes to. Models are validated against the new single source of truth KNOWN_AGENT_MODELS (src/scrum/agent-model.ts), which the dashboard's ALLOWED_AGENT_MODELS now re-exports, so the server and the dashboard can no longer drift. The sprint-instructions text and the empty-team hint advertised a create_agent tool that never existed; they now point at update_agent / reset_agents.
• Claude Opus 5 in the model catalog — claude-opus-5 is offered by the dashboard picker and accepted everywhere; the QA factory seed moves claude-opus-4-8 → claude-opus-5. claude-opus-4-8 joins claude-sonnet-4-6 as a legacy id (rendered and editable, not offered for new picks).

Fixed

• A model or provider name in assigned_to silently routed to sonnet — create_ticket and update_ticket accepted any string on the single-assignee path (only the agents[] path validated roles), so a ticket assigned to "opus" or "glm" found no agent in buildModelRoutingSection and got the sonnet fallback with no error anywhere. Both tools now reject an assigned_to that is not a roster role (message lists the valid roles and points at impl:* tags for the runtime); an empty roster (agentless mode) still accepts anything. (unknownRosterRole)