Fix dashboard integration test: use title case collection names

Update TestRestoreSystemCollection_ValidNames to use the correct
title case format for system collection names.

The API handler validates these specific collection names:
- "Continue Reading"
- "Recently Added"
- "Recently Read"
- "Not Started"

The test was previously using kebab-case names (e.g., "continue-reading")
which were being rejected by the validation logic with 400 Bad Request.

This aligns the test with the updated collection name format used
throughout the application.

cmd/server/tests/dashboard_integration_test.go

@@ -209,7 +209,7 @@ func (s *DashboardIntegrationTestSuite) TestRestoreSystemCollection_Unauthorized
 func (s *DashboardIntegrationTestSuite) TestRestoreSystemCollection_ValidNames() {
 	token := s.setup.Token
 
-	validCollections := []string{"continue-reading", "recently-added", "recently-read", "not-started"}
+	validCollections := []string{"Continue Reading", "Recently Added", "Recently Read", "Not Started"}
 
 	for _, collName := range validCollections {
 		s.T().Run(collName, func(t *testing.T) {