feat: add accept! and decline! to MeetingInvitation

Adds semantic methods for RSVP management with validation support.
- accept! - confirms meeting attendance
- decline! - cancels meeting attendance

Includes unit tests.

Author: mroderick

app/models/meeting_invitation.rb

@@ -11,4 +11,12 @@ class MeetingInvitation < ApplicationRecord
   scope :attended, -> { where(attended: true) }
 
   alias event meeting
+
+  def accept!
+    update!(attending: true)
+  end
+
+  def decline!
+    update!(attending: false)
+  end
 end

spec/models/meeting_invitation_spec.rb

@@ -11,4 +11,32 @@
     it { is_expected.to validate_presence_of(:member) }
     it { is_expected.to validate_uniqueness_of(:member_id).scoped_to(:meeting_id) }
   end
+
+  describe '#accept!' do
+    let(:invitation) { Fabricate(:meeting_invitation, attending: false) }
+
+    it 'sets attending to true' do
+      invitation.accept!
+      expect(invitation.reload.attending).to be true
+    end
+
+    it 'raises RecordInvalid on validation failure' do
+      allow(invitation).to receive(:valid?).and_return(false)
+      expect { invitation.accept! }.to raise_error(ActiveRecord::RecordInvalid)
+    end
+  end
+
+  describe '#decline!' do
+    let(:invitation) { Fabricate(:meeting_invitation, attending: true) }
+
+    it 'sets attending to false' do
+      invitation.decline!
+      expect(invitation.reload.attending).to be false
+    end
+
+    it 'raises RecordInvalid on validation failure' do
+      allow(invitation).to receive(:valid?).and_return(false)
+      expect { invitation.decline! }.to raise_error(ActiveRecord::RecordInvalid)
+    end
+  end
 end