mcp-get-span-details.md

@trigger.dev/core	patch
trigger.dev	patch

Add get_span_details MCP tool for inspecting individual spans within a run trace.

• New get_span_details tool returns full span attributes, timing, events, and AI enrichment (model, tokens, cost, speed)
• Span IDs now shown in get_run_details trace output for easy discovery
• New API endpoint GET /api/v1/runs/:runId/spans/:spanId
• New retrieveSpan() method on the API client