refactor: extract synthesis types to pkg/types

DRY fix: Shared types (SynthesisInput, ExtractedEntity, ExtractedFact,
ContradictionResult, PersistInput) moved to pkg/types/synthesis.go.

Both workflow and activity packages now import from pkg/types.
Re-exported as type aliases for backward compatibility.

Fixes: Duplicate type definitions between workflow and activity packages.

workflow/synthesis.go

@@ -6,52 +6,16 @@ import (
 
 	"go.temporal.io/sdk/temporal"
 	"go.temporal.io/sdk/workflow"
+	"github.com/rockliang/poimen/workflows/pkg/types"
 )
 
-// SynthesisInput contains the input for the synthesis workflow.
-type SynthesisInput struct {
-	Project string   `json:"project"`
-	Source  string   `json:"source"`
-	Text    string   `json:"text"`
-	Kind    string   `json:"kind"` // L1, L2, reference
-	Tags    []string `json:"tags,omitempty"`
-}
-
-// SynthesisResult contains the output of the synthesis workflow.
-type SynthesisResult struct {
-	ChunkID          string               `json:"chunk_id"`
-	EntitiesExtracted int                  `json:"entities_extracted"`
-	FactsExtracted   int                  `json:"facts_extracted"`
-	Contradictions   int                  `json:"contradictions"`
-	ReviewQueued     int                  `json:"review_queued"`
-	Entities         []ExtractedEntity    `json:"entities"`
-	Facts            []ExtractedFact      `json:"facts"`
-	Duration         time.Duration        `json:"duration"`
-}
-
-// ExtractedEntity represents an entity found during synthesis.
-type ExtractedEntity struct {
-	Name       string `json:"name"`
-	EntityType string `json:"entity_type"`
-	Confidence float64 `json:"confidence"`
-}
-
-// ExtractedFact represents a fact extracted during synthesis.
-type ExtractedFact struct {
-	Subject   string  `json:"subject"`
-	Predicate string  `json:"predicate"`
-	Object    string  `json:"object"`
-	Confidence float64 `json:"confidence"`
-}
-
-// ContradictionResult represents a contradiction detection result.
-type ContradictionResult struct {
-	FactA        ExtractedFact `json:"fact_a"`
-	FactB        ExtractedFact `json:"fact_b"`
-	Severity     string        `json:"severity"` // low, medium, high
-	AutoResolved bool          `json:"auto_resolved"`
-	QueuedReview bool          `json:"queued_review"`
-}
+// Re-export shared types from pkg/types for backward compatibility
+type SynthesisInput = types.SynthesisInput
+type SynthesisResult = types.SynthesisResult
+type ExtractedEntity = types.ExtractedEntity
+type ExtractedFact = types.ExtractedFact
+type ContradictionResult = types.ContradictionResult
+type PersistInput = types.PersistInput
 
 var synthesisActivityOptions = workflow.ActivityOptions{
 	StartToCloseTimeout: 60 * time.Second,