`explore --metric` uses wrong dataset for trace metrics

[sentry-junior]

sentry explore --metric <name> --dataset metrics cannot resolve SDK v10 trace metrics because the --metric auto-resolver queries dataset=metrics (the legacy DDM/release-health surface backed by OrganizationReleaseHealthDataEndpoint). SDK v10 Sentry.metrics.count() emits trace_metric envelope items stored in dataset=tracemetrics, which is the dataset the Sentry Explore Metrics UI uses (DiscoverDatasets.TRACEMETRICS).

Evidence

The Sentry MCP server emits Sentry.metrics.count("app.oauth.skill_granted", ...) via @sentry/cloudflare@10.35.0 with enableMetrics: true. The metric has 21K+ data points over 30 days, confirmed via direct API:

dataset=tracemetrics → sum(value,app.oauth.skill_granted,counter,none) = 21,341 ✅
dataset=metrics     → "could not be resolved" ❌

The CLI brute-forces MRI resolution against the events API with dataset=metrics, trying every (type, unit) combination. All return empty because the metric lives in tracemetrics.

Sentry source reference

The Explore Metrics UI uses DiscoverDatasets.TRACEMETRICS (static/app/views/explore/metrics/hooks/useMetricAggregatesTable.tsx) with field format sum(value, metricName, metricType, unit) against /organizations/{org}/events/.

Expected behavior

sentry explore --metric app.oauth.skill_granted --dataset metrics should resolve the metric from the tracemetrics dataset (or the --dataset metrics alias should route to tracemetrics).

Action taken on behalf of David Cramer.