Implemented the initial Go framework

internal/builtin/merge.go

@@ -0,0 +1,52 @@
+package builtin
+
+import (
+	"context"
+	"sort"
+
+	"gitea.maximumdirect.net/eric/seriatim/internal/config"
+	"gitea.maximumdirect.net/eric/seriatim/internal/model"
+	"gitea.maximumdirect.net/eric/seriatim/internal/report"
+)
+
+type placeholderMerger struct{}
+
+func (placeholderMerger) Name() string {
+	return "placeholder-merger"
+}
+
+func (placeholderMerger) Merge(ctx context.Context, in []model.CanonicalTranscript, cfg config.Config) (model.MergedTranscript, []report.Event, error) {
+	if err := ctx.Err(); err != nil {
+		return model.MergedTranscript{}, nil, err
+	}
+
+	segments := make([]model.Segment, 0)
+	for _, transcript := range in {
+		segments = append(segments, transcript.Segments...)
+	}
+
+	sort.SliceStable(segments, func(i, j int) bool {
+		left := segments[i]
+		right := segments[j]
+		if left.Start != right.Start {
+			return left.Start < right.Start
+		}
+		if left.End != right.End {
+			return left.End < right.End
+		}
+		if left.Source != right.Source {
+			return left.Source < right.Source
+		}
+		if left.SourceSegmentIndex != right.SourceSegmentIndex {
+			return left.SourceSegmentIndex < right.SourceSegmentIndex
+		}
+		return left.Speaker < right.Speaker
+	})
+
+	return model.MergedTranscript{
+			Segments:      segments,
+			OverlapGroups: nil,
+		}, []report.Event{
+			report.Info("merge", "placeholder-merger", "merged placeholder canonical transcript(s)"),
+		}, nil
+}