Expand module contracts for references and normalizer LLM access

internal/modules/input/seriatim/config_test.go

@@ -209,6 +209,8 @@ type fakeChunker struct{}
 
 func (fakeChunker) Key() string { return "fake/chunk" }
 
+func (fakeChunker) ReferenceSlots() []contracts.ReferenceSlot { return nil }
+
 func (fakeChunker) Chunk(ctx context.Context, req contracts.ChunkRequest) (contracts.ChunkResult, error) {
 	return contracts.ChunkResult{}, nil
 }

internal/modules/input/seriatim/runner_test.go

@@ -157,6 +157,10 @@ func (runnerSeriatimChunker) Key() string {
 	return "fake/chunk"
 }
 
+func (runnerSeriatimChunker) ReferenceSlots() []contracts.ReferenceSlot {
+	return nil
+}
+
 func (runnerSeriatimChunker) Chunk(ctx context.Context, req contracts.ChunkRequest) (contracts.ChunkResult, error) {
 	return contracts.ChunkResult{
 		Chunks: []contracts.SourceChunk{