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/router/frontend.go

@@ -158,18 +158,17 @@ func registerFrontendRoutes(cfg *Config) {
 		if err != nil {
 			return c.HTML(http.StatusInternalServerError, "Error loading user")
 		}
-		deviceData, err := cfg.DeviceHandler.GetDevicesData(c)
+		devices, err := cfg.DeviceHandler.GetDevicesData(c)
 		if err != nil {
 			return c.HTML(http.StatusInternalServerError, "Error loading devices")
 		}
-		pendingData, err := cfg.DeviceHandler.GetPendingRegistrationsData(c)
+		pendingMaps, err := cfg.DeviceHandler.GetPendingRegistrationsData(c)
 		if err != nil {
 			return c.HTML(http.StatusInternalServerError, "Error loading pending")
 		}
-		devicesList := convertDevices(deviceData)
-		pendingList := convertPending(pendingData)
+		pendingList := convertPending(pendingMaps)
 		var buf bytes.Buffer
-		err = templates.Devices(user, devicesList, pendingList).Render(c.Request().Context(), &buf)
+		err = templates.Devices(user, devices, pendingList).Render(c.Request().Context(), &buf)
 		if err != nil {
 			return err
 		}