refactor: import synthesis types from pkg/types

DRY fix: Activity package now imports shared types from pkg/types/synthesis.go.
Re-exported as type aliases for backward compatibility.

Removes duplicate type definitions, coordinates with PR #12.

activity/synthesis.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 
 	"github.com/rockliang/poimen/workflows/internal/memory"
+	"github.com/rockliang/poimen/workflows/pkg/types"
 )
 
 // SynthesisActivities holds dependencies for synthesis pipeline activities.
@@ -22,49 +23,12 @@ func NewSynthesisActivities(memClient *memory.Client) *SynthesisActivities {
 	return &SynthesisActivities{memClient: memClient}
 }
 
-// SynthesisInput mirrors workflow.SynthesisInput for activity deserialization.
-type SynthesisInput struct {
-	Project string   `json:"project"`
-	Source  string   `json:"source"`
-	Text    string   `json:"text"`
-	Kind    string   `json:"kind"`
-	Tags    []string `json:"tags,omitempty"`
-}
-
-// 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"`
-	AutoResolved bool          `json:"auto_resolved"`
-	QueuedReview bool          `json:"queued_review"`
-}
-
-// 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"`
-}
+// Re-export shared types from pkg/types
+type SynthesisInput = types.SynthesisInput
+type ExtractedEntity = types.ExtractedEntity
+type ExtractedFact = types.ExtractedFact
+type ContradictionResult = types.ContradictionResult
+type PersistInput = types.PersistInput
 
 // ChunkAndEmbedActivity chunks text and generates a chunk ID.
 // Stage 1: Creates a deterministic chunk ID from content hash,