Basic donation records

Adds donation model/table and basic manual management in the admin
panel, as well as basic listing of users' own donations.

spec/factories/donations.rb

@@ -0,0 +1,9 @@
+FactoryBot.define do
+  factory :donation do
+    user_id { 1 }
+    amount_sats { 100000 }
+    amount_eur { 10 }
+    amount_usd { 13 }
+    public_name { nil }
+  end
+end

spec/helpers/donations_helper_spec.rb

@@ -0,0 +1,15 @@
+require 'rails_helper'
+
+# Specs in this file have access to a helper object that includes
+# the DonationsHelper. For example:
+#
+# describe DonationsHelper do
+#   describe "string concat" do
+#     it "concats two strings with spaces" do
+#       expect(helper.concat_strings("this","that")).to eq("this that")
+#     end
+#   end
+# end
+RSpec.describe DonationsHelper, type: :helper do
+  pending "add some examples to (or delete) #{__FILE__}"
+end

spec/models/donation_spec.rb

@@ -0,0 +1,5 @@
+require 'rails_helper'
+
+RSpec.describe Donation, type: :model do
+  pending "add some examples to (or delete) #{__FILE__}"
+end