Validate presence of name for public project

Somewhat surprisingly there is currently no validation for the presence
of `name` on the `Project` model itself, although I suspect the name is
probably implicitly guaranteed not to be blank by the clients of
editor-api.

Since admin users in experience-cs are going to be entering the name
manually in the administrate UI, I want to protect against a blank name
and I want to be able to provide a sensible error message if none is
set.

Ideally I'd add a validation to the `Project` model itself. However,
since I don't have access [1] to staging or production data for
`editor-api`, I can't be sure that some existing projects would become
invalid. So as before I've added the validation to the `PublicProject`
wrapper class which means the validation will only be used in the
context of the `Api::PublicProjectsController`.

[1]: https://raspberrypifoundation.slack.com/archives/C08831T17H6/p1747900618263229

Author: floehopper

app/models/public_project.rb

@@ -5,9 +5,10 @@ class PublicProject
 
   attr_reader :project
 
-  delegate :identifier, to: :project
+  delegate :identifier, :name, to: :project
 
   validates :identifier, format: { with: PhraseIdentifier::PATTERN, allow_blank: true }
+  validates :name, presence: true
 
   def initialize(project)
     @project = project

spec/concepts/public_project/create_spec.rb

@@ -7,12 +7,13 @@
     subject(:create_project) { described_class.call(project_hash:) }
 
     let(:identifier) { 'foo-bar-baz' }
+    let(:name) { 'Foo bar baz' }
     let(:project_hash) do
       {
         identifier:,
         locale: 'en',
         project_type: Project::Types::SCRATCH,
-        name: 'Foo bar baz'
+        name:
       }
     end
 
@@ -67,5 +68,17 @@
         expect(create_project[:error]).to eq('Error creating project: Validation failed: Identifier is invalid')
       end
     end
+
+    context 'when name is blank' do
+      let(:name) { '' }
+
+      it 'returns failure' do
+        expect(create_project.failure?).to be(true)
+      end
+
+      it 'returns error message' do
+        expect(create_project[:error]).to eq("Error creating project: Validation failed: Name can't be blank")
+      end
+    end
   end
 end