Refactor: Eliminate duplicate types - Use handler types directly

- Deleted templates.CollectionDetailData - using templates.CollectionData everywhere
- Deleted templates.BookData - using handlers.BookInfo everywhere
- Deleted templates.DeviceData - using handlers.DeviceInfo everywhere
- Deleted templates.ProgressItemData - using handlers.ProgressWithMedia everywhere
- Deleted templates.convertDevices() helper - Use handlers types directly in templates
- Enhanced handlers.ProgressWithMedia with device metadata fields
- Added handlers.getDeviceIcon() helper
- Updated all templates to import handlers package
- Cleaned up unused imports

This aligns codebase with templ's design philosophy (use Go types directly, no parallel type system)

internal/handlers/collections.go

@@ -63,6 +63,13 @@ type UpdateDeviceMappingRequest struct {
 	SyncDirection   string `json:"sync_direction" validate:"required,oneof=bidirectional book_to_device device_to_book none"`
 }
 
+type BookInfo struct {
+	MediaItemID    string `json:"media_item_id"`
+	Title          string `json:"title"`
+	Author         string `json:"author"`
+	CoverImagePath string `json:"cover_image_path"`
+}
+
 func (h *CollectionHandler) CreateCollection(c echo.Context) error {
 	user := c.Get("user").(database.Users)
 	userUUID := uuid.UUID(user.ID.Bytes)
@@ -171,13 +178,6 @@ func (h *CollectionHandler) GetCollection(c echo.Context) error {
 		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
 	}
 
-	type BookInfo struct {
-		MediaItemID    string `json:"media_item_id"`
-		Title          string `json:"title"`
-		Author         string `json:"author"`
-		CoverImagePath string `json:"cover_image_path"`
-	}
-
 	bookList := make([]BookInfo, 0, len(books))
 	for _, book := range books {
 		bookList = append(bookList, BookInfo{