Introduce architettura multi-sport con catalogo, engine scoring e overlay.

Catalogo sport in YAML, board implicito, engine per volley/basket/timed/racket/timer/generic, regia e app Android allineate.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/spec/domain/sports/catalog_spec.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+RSpec.describe Sports::Catalog do
+  describe ".find" do
+    it "restituisce pallavolo con board volley" do
+      entry = described_class.find("pallavolo")
+      expect(entry[:board]).to eq("volley")
+      expect(entry[:overlay]).to eq("volley")
+      expect(entry[:default_rules]["sets_to_win"]).to eq(3)
+    end
+
+    it "mappa legacy volleyball" do
+      expect(described_class.normalize_key("volleyball")).to eq("pallavolo")
+    end
+
+    it "altro usa board generic" do
+      entry = described_class.find("altro")
+      expect(entry[:board]).to eq("generic")
+      expect(entry[:overlay]).to eq("none")
+    end
+  end
+
+  describe ".as_api_list" do
+    it "include tutti gli sport configurati" do
+      keys = described_class.as_api_list.map { |e| e[:key] }
+      expect(keys).to include("pallavolo", "basket", "calcio_a_5", "tennis", "ginnastica_artistica", "altro")
+    end
+  end
+end