Initialize narratio Go module and CLI scaffold

internal/adapters/analyzer/runner.go

@@ -0,0 +1,20 @@
+// Package analyzer declares the adapter contract for artifact analysis generation.
+package analyzer
+
+import "context"
+
+// Runner is a placeholder adapter interface for session artifact generation.
+type Runner interface {
+	Run(ctx context.Context, req AnalysisRequest) (AnalysisResult, error)
+}
+
+// AnalysisRequest is a placeholder analyzer input.
+type AnalysisRequest struct {
+	ProcessedTranscriptPath string
+	OutputDir               string
+}
+
+// AnalysisResult is a placeholder analyzer output.
+type AnalysisResult struct {
+	ArtifactPaths []string
+}