feat(handlers): Add helper methods for hybrid SSR

- Add GetPendingRegistrationsData() to DeviceHandler
- Add GetQueueData() to QueueHandler
- Add template types: DeviceData, PendingRegistrationData, ConflictData, QueueItemData
- Add collection types: CollectionData, CollectionDetailData, BookData

All changes are non-breaking and preserve API compatibility

internal/handlers/queue.go

@@ -146,11 +146,11 @@ func (h *QueueHandler) ListDeviceQueueItems(c echo.Context) error {
 	})
 }
 
-func (h *QueueHandler) ListAllQueueItems(c echo.Context) error {
+func (h *QueueHandler) GetQueueData(c echo.Context) ([]QueueItemResponse, error) {
 	user := MustGetAuthenticatedUser(c)
 
 	if user.Role != "admin" {
-		return echo.NewHTTPError(http.StatusForbidden, "admin access required")
+		return nil, echo.NewHTTPError(http.StatusForbidden, "admin access required")
 	}
 
 	limit := 50
@@ -173,21 +173,15 @@ func (h *QueueHandler) ListAllQueueItems(c echo.Context) error {
 	})
 
 	if err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, "failed to list queue items")
+		return nil, err
 	}
 
 	response := make([]QueueItemResponse, 0, len(items))
 	for _, item := range items {
-		mediaTitle := textPtrToString(item.MediaTitle)
-
 		response = append(response, QueueItemResponse{
 			ID:           uuid.UUID(item.ID.Bytes).String(),
 			DeviceID:     uuid.UUID(item.DeviceID.Bytes).String(),
-			DeviceName:   item.DeviceName,
-			DeviceType:   item.DeviceType,
 			MediaItemID:  uuidPtrToString(item.MediaItemID),
-			MediaTitle:   mediaTitle,
-			UserEmail:    item.UserEmail,
 			SyncType:     item.SyncType,
 			Priority:     item.Priority.Int32,
 			Attempts:     item.Attempts.Int32,
@@ -199,11 +193,18 @@ func (h *QueueHandler) ListAllQueueItems(c echo.Context) error {
 		})
 	}
 
+	return response, nil
+}
+
+func (h *QueueHandler) ListAllQueueItems(c echo.Context) error {
+	response, err := h.GetQueueData(c)
+	if err != nil {
+		return err
+	}
+
 	return c.JSON(http.StatusOK, map[string]interface{}{
-		"items":  response,
-		"count":  len(response),
-		"limit":  limit,
-		"offset": offset,
+		"items": response,
+		"count": len(response),
 	})
 }