fix: remove duplicate PersistInput type definition

Type already re-exported from pkg/types at top of file

workflow/synthesis.go

@@ -123,14 +123,3 @@ func SynthesisWorkflow(ctx workflow.Context, input SynthesisInput) (*SynthesisRe
 
 	return result, nil
 }
-
-// PersistInput groups all synthesis results for persistence.
-type PersistInput struct {
-	ChunkID        string                `json:"chunk_id"`
-	Project        string                `json:"project"`
-	Source         string                `json:"source"`
-	Kind           string                `json:"kind"`
-	Entities       []ExtractedEntity     `json:"entities"`
-	Facts          []ExtractedFact       `json:"facts"`
-	Contradictions []ContradictionResult `json:"contradictions"`
-}