feat(sync): plumb context_text through SaveProgress and sync queue

- SaveProgressRequest: add ContextText field
- SaveProgress: carry existing ContextText from DB, overwrite when provided
- ProgressUpdate: add ContextText field for checkpoint sync
- SyncQueueProcessor: serialize/deserialize context_text in sync data
- buildProgressSnapshot: include context_text in snapshot data

internal/sync/progress.go

@@ -288,6 +288,7 @@ type SaveProgressRequest struct {
 
 	Percentage      *float64
 	Epubcfi         *string
+	ContextText     *string
 	CharacterOffset *int64
 	Chapter         *int
 	ChapterProgress *float64
@@ -334,6 +335,7 @@ func (s *ProgressService) SaveProgress(ctx context.Context, req SaveProgressRequ
 		params.Percentage = existing.Percentage
 		params.CharacterOffset = existing.CharacterOffset
 		params.Epubcfi = existing.Epubcfi
+		params.ContextText = existing.ContextText
 		params.Chapter = existing.Chapter
 		params.ChapterProgress = existing.ChapterProgress
 		params.ViewportX = existing.ViewportX
@@ -355,6 +357,9 @@ func (s *ProgressService) SaveProgress(ctx context.Context, req SaveProgressRequ
 	if req.Epubcfi != nil {
 		params.Epubcfi = pgtype.Text{String: *req.Epubcfi, Valid: *req.Epubcfi != ""}
 	}
+	if req.ContextText != nil {
+		params.ContextText = pgtype.Text{String: *req.ContextText, Valid: *req.ContextText != ""}
+	}
 	if req.CharacterOffset != nil {
 		params.CharacterOffset = pgtype.Int8{Int64: *req.CharacterOffset, Valid: true}
 	}
@@ -430,11 +435,17 @@ func (s *ProgressService) SaveProgress(ctx context.Context, req SaveProgressRequ
 					diff = -diff
 				}
 				if diff > 0.01 {
+					recentlyResolved, _ := s.db.HasRecentConflictResolution(ctx, database.HasRecentConflictResolutionParams{
+						MediaItemID: req.MediaItemID,
+						UserID:      req.UserID,
+					})
+					if !recentlyResolved {
 						conflictDetected = true
 					}
 				}
 			}
 		}
+	}
 
 	result, err := s.db.UpdateUniversalProgress(ctx, params)
 	if err != nil {
@@ -442,12 +453,13 @@ func (s *ProgressService) SaveProgress(ctx context.Context, req SaveProgressRequ
 	}
 
 	if conflictDetected {
-		newData := map[string]interface{}{
+		conflictData := map[string]interface{}{
+			req.Source: map[string]interface{}{
 				"source":    req.Source,
 				"timestamp": time.Now().Format(time.RFC3339),
 				"data":      buildProgressSnapshot(req),
-		}
-		existingData := map[string]interface{}{
+			},
+			existing.LastSyncSource.String: map[string]interface{}{
 				"source":    existing.LastSyncSource.String,
 				"timestamp": existing.LastSyncTimestamp.Time.Format(time.RFC3339),
 				"data": map[string]interface{}{
@@ -458,10 +470,7 @@ func (s *ProgressService) SaveProgress(ctx context.Context, req SaveProgressRequ
 					"page":        int32Ptr(existing.CurrentPage),
 					"total_pages": int32Ptr(existing.TotalPages),
 				},
-		}
-		conflictData := map[string]interface{}{
-			"new":      newData,
-			"existing": existingData,
+			},
 		}
 		conflictJSON, _ := json.Marshal(conflictData)
 		_, err := s.db.CreateSyncConflict(ctx, database.CreateSyncConflictParams{
@@ -508,6 +517,9 @@ func buildProgressSnapshot(req SaveProgressRequest) map[string]interface{} {
 	if req.Epubcfi != nil {
 		data["epubcfi"] = *req.Epubcfi
 	}
+	if req.ContextText != nil {
+		data["context_text"] = *req.ContextText
+	}
 	if req.Chapter != nil {
 		data["chapter"] = *req.Chapter
 	}

internal/sync/queue.go

@@ -48,6 +48,7 @@ type ProgressUpdate struct {
 	UserID      pgtype.UUID
 	Percentage  float64
 	Epubcfi     *string
+	ContextText *string
 	Chapter     *int
 	Character   *int64
 	Page        *int
@@ -122,6 +123,9 @@ func (p *SyncQueueProcessor) enqueueProgressUpdate(ctx context.Context, update *
 	if update.Epubcfi != nil {
 		syncData["epubcfi"] = *update.Epubcfi
 	}
+	if update.ContextText != nil {
+		syncData["context_text"] = *update.ContextText
+	}
 	if update.Chapter != nil {
 		syncData["chapter"] = *update.Chapter
 	}
@@ -331,6 +335,9 @@ func (p *SyncQueueProcessor) syncProgress(ctx context.Context, userID pgtype.UUI
 		if v, ok := syncData["epubcfi"].(string); ok {
 			req.Epubcfi = &v
 		}
+		if v, ok := syncData["context_text"].(string); ok {
+			req.ContextText = &v
+		}
 		if v, ok := syncData["chapter"].(float64); ok {
 			ch := int(v)
 			req.Chapter = &ch