Add a support-ticket triage example graph

[madeinplutofabio]

Summary

Adopters quickly grasp "agent receives a ticket, NCP routes it". It is a canonical example of a workflow that benefits from a deterministic graph. A second concrete example alongside lead-qualification (#29) gives adopters two distinct scenarios to learn from.

Acceptance criteria

• Add examples/graphs/support-ticket-triage/graph.yaml.
• Input: { ticket_subject, ticket_body, customer_tier }.
• Output: { category, priority, confidence, suggested_queue, reason }.
• Include at least 5 fixture inputs under examples/graphs/support-ticket-triage/fixtures/.
• Include the expected output JSON for each fixture.
• Document how to expose the graph through ncp-mcp-server in a brief README in the graph directory.

Why this matters

Makes NCP feel practical without needing a complex demo. Ticket triage is a workflow most teams recognize and can imagine adopting.

Where to read

• examples/graphs/echo-pipeline/ for the directory structure to mirror
• docs/MCP_ADAPTER.md §5 for the response shape an MCP-compatible host will see