Function dispatch_action 

pub async fn dispatch_action(
    service: &SomaService,
    action: &SomaAction,
    surface: &str,
) -> Result<Value>

Unified dispatch seam shared by every surface (MCP, REST, CLI).

Wraps execute_service_action with consistent timing, structured logging, and metrics so each surface gets identical observability for free. The shims call this instead of execute_service_action directly; execute_service_action remains public for callers that have already established their own span.

surface is a short, low-cardinality label such as "mcp", "rest", or "cli". Action parameters are intentionally never logged or labelled — they can carry credentials, and per-value labels would explode metric cardinality.