Refactor frontend components and enhance API integration

- Updated frontend-nuxt.mdc to specify usage of composables for API calls.
- Added new AuthCard and ConfirmModal components for improved UI consistency.
- Introduced UserAvatar component for user profile display, replacing previous Gravatar implementation.
- Implemented useFormSubmit composable for handling form submissions with loading and error states.
- Enhanced vitest.config.ts to include coverage reporting for composables and components.
- Removed deprecated useAdminApi and useAuth composables to streamline API interactions.
- Updated login and setup pages to utilize new components and composables for better user experience.

internal/app/services/export.go

@@ -30,6 +30,7 @@ type ExportService struct {
 }
 
 // NewExportService creates an ExportService with the given store and map service.
+// Uses direct args (two dependencies) rather than a deps struct.
 func NewExportService(st *store.Store, mapSvc *MapService) *ExportService {
 	return &ExportService{st: st, mapSvc: mapSvc}
 }
@@ -190,7 +191,9 @@ func (s *ExportService) Merge(ctx context.Context, zr *zip.Reader) error {
 			gridRaw := grids.Get([]byte(gid))
 			if gridRaw != nil {
 				gd := app.GridData{}
-				json.Unmarshal(gridRaw, &gd)
+				if err := json.Unmarshal(gridRaw, &gd); err != nil {
+					return err
+				}
 				ops = append(ops, TileOp{
 					MapID: gd.Map,
 					X:     gd.Coord.X,
@@ -265,7 +268,9 @@ func (s *ExportService) processMergeJSON(
 		gridRaw := grids.Get([]byte(v))
 		if gridRaw != nil {
 			gd := app.GridData{}
-			json.Unmarshal(gridRaw, &gd)
+			if err := json.Unmarshal(gridRaw, &gd); err != nil {
+				return err
+			}
 			existingMaps[gd.Map] = struct{ X, Y int }{gd.Coord.X - c.X, gd.Coord.Y - c.Y}
 		}
 	}
@@ -301,7 +306,9 @@ func (s *ExportService) processMergeJSON(
 		mi := app.MapInfo{}
 		mraw := mapB.Get([]byte(strconv.Itoa(id)))
 		if mraw != nil {
-			json.Unmarshal(mraw, &mi)
+			if err := json.Unmarshal(mraw, &mi); err != nil {
+				return err
+			}
 		}
 		if mi.Priority {
 			mapid = id
@@ -333,7 +340,9 @@ func (s *ExportService) processMergeJSON(
 	if len(existingMaps) > 1 {
 		grids.ForEach(func(k, v []byte) error {
 			gd := app.GridData{}
-			json.Unmarshal(v, &gd)
+			if err := json.Unmarshal(v, &gd); err != nil {
+				return err
+			}
 			if gd.Map == mapid {
 				return nil
 			}
@@ -349,7 +358,9 @@ func (s *ExportService) processMergeJSON(
 				}
 				tileraw := zoom.Get([]byte(gd.Coord.Name()))
 				if tileraw != nil {
-					json.Unmarshal(tileraw, &td)
+					if err := json.Unmarshal(tileraw, &td); err != nil {
+						return err
+					}
 				}
 
 				gd.Map = mapid