Merge branch 'feat/565-add-metric-tooltip' into metric-store-tickets

Resolve conflicts in the generated GraphQL code by regenerating it against
the merged schema. cc-lib v2.13.0 adds Tooltip to schema.MetricConfig and
schema.GlobalMetricListItem, so gqlgen now binds the tooltip field directly
and the hand-written globalMetricListItem/metricConfig resolvers introduced
on the tooltip branch are no longer needed.

Also migrate to the cc-lib v2.13.0 metric container types, which changed
from bare maps to structs carrying array-valued metric groups:

  schema.JobData          map -> {Metrics, Groups}
  schema.ScopedJobStats   map -> {Metrics, Groups}
  job.Statistics          map -> schema.JobStatisticsSet{Metrics, Groups}

Callers index .Metrics, return the zero struct instead of nil, and
deepCopy/DecodeJobStats now also carry the Groups payload through.
archive.GetStatistics returns the full JobStatisticsSet so group
statistics survive the round trip.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

api/schema.graphqls

@@ -143,6 +143,7 @@ type MetricConfig {
   alert: Float!
   lowerIsBetter: Boolean
   subClusters: [SubClusterConfig!]!
+  tooltip: String
 }
 
 type Tag {
@@ -306,6 +307,7 @@ type GlobalMetricListItem {
   unit: Unit!
   scope: MetricScope!
   footprint: String
+  tooltip: String
   availability: [ClusterSupport!]!
 }