Summary

Add the central ADO Backlog Manager orchestrator agent that ties together all
workflows, tools, and handoff buttons. This is the final PR in the sequence,
merged after all instruction and prompt files are in place.

Part of #774. Depends on all other child issues (#776, #777, #778, #779).

Changes

New Files

• .github/agents/ado/ado-backlog-manager.agent.md
  • 22 ADO MCP tools across 5 categories
  • 10 handoff buttons (Discover, Triage, Sprint, Execute, Add, Plan, PRD, Build, PR, Save)
  • 3-phase Required Phases (Intent Classification → Workflow Dispatch → Summary)
  • 9-row workflow routing table
  • Three-tier autonomy reference
  • Content format detection reference (delegates to planning instructions)
  • Interaction templates reference (delegates to ado-interaction-templates)
  • Session persistence and state management
  • disable-model-invocation: true

Modified Files

• collections/ado.collection.yml (agent entry)
• collections/ado.collection.md (backlog management bullet)

Acceptance Criteria

• ado-backlog-manager.agent.md created with full orchestrator spec
• All 10 handoff buttons reference valid prompts/agents
• Collection manifest includes agent entry
• Collection description updated with backlog management bullet
• Plugin generation passes (npm run plugin:generate)
• Markdown linting passes