Fix timeline chart bucket alignment and precision (#2129)

Replaced integer duration division with `time.Truncate(granularity)` to ensure mathematically perfect bucket alignment and prevent edge-case tracking bugs over long periods. Also swapped map keys from `time.Time` to `int64` (Unix timestamps) to avoid any potential strict location/pointer reference mapping issues when processing Unmarshalled `time.Time` types. Added tests with unaligned data to confirm correctness.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: KCarretto <16250309+KCarretto@users.noreply.github.com>

Author: KCarretto

tavern/internal/graphql/metrics.resolvers.go

@@ -59,11 +59,11 @@ func TestMetrics_QuestTimelineChart(t *testing.T) {
 		Save(ctx)
 	require.NoError(t, err)
 
-	// Quest 3 at startTime + 3s (Bucket 3)
+	// Quest 3 at startTime + 3.5s (Unaligned! Should be perfectly aligned into Bucket 3)
 	_, err = client.Quest.Create().
 		SetName("quest3").
 		SetTome(tome1).
-		SetCreatedAt(startTime.Add(3 * time.Second)).
+		SetCreatedAt(startTime.Add(3500 * time.Millisecond)).
 		Save(ctx)
 	require.NoError(t, err)
 

tavern/internal/graphql/metrics_test.go

@@ -45,12 +45,12 @@ func WithBuilderCA(builderCA *x509.Certificate) Option {
 // NewSchema creates a graphql executable schema.
 func NewSchema(client *ent.Client, importer RepoImporter, options ...func(*Resolver)) graphql.ExecutableSchema {
 	resolver := &Resolver{
-		client:       client,
-		importer:     importer,
+		client:   client,
+		importer: importer,
 	}
 	for _, opt := range options {
-      opt(resolver)
-    }
+		opt(resolver)
+	}
 	cfg := generated.Config{
 		Resolvers: resolver,
 	}