List spans

List individual spans using UQL (Uptrace Query Language). Use this to inspect specific span details, search for errors, or browse recent operations. Supports WHERE filters (e.g. where service_name = 'myservice', where _status_code = 'error', where _dur_ms > 100ms), full-text search (e.g. word1|word2 -excluded), system filtering (e.g. httpserver:all, db:postgresql, log:error), duration filtering in milliseconds, and sorting by any span field. Span fields use underscore prefix: _name, _dur_ms, _status_code, _time, _trace_id, _kind. Attributes use dot-to-underscore: service.name becomes service_name. Returns individual span objects with attrs, timing, and status. Use list_span_groups instead when you need aggregated metrics (count, avg, p99). Use list_traces instead when you need to find traces matching multi-span criteria. Documentation: https://uptrace.dev/features/querying/spans