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/app/domain/sports/rules_schema.rb

@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+module Sports
+  class RulesSchema
+    INTEGER_RULES = {
+      "volley" => %w[sets_to_win points_per_set points_deciding_set min_point_lead],
+      "racket" => %w[sets_to_win points_per_set points_deciding_set min_point_lead],
+      "basket" => %w[periods period_duration_secs overtime_duration_secs],
+      "timed" => %w[periods period_duration_secs overtime_duration_secs],
+      "timer" => [],
+      "generic" => []
+    }.freeze
+
+    def self.validate!(board_type, rules)
+      board = board_type.to_s
+      return if board == "generic" || board == "timer"
+
+      hash = rules.is_a?(Hash) ? rules : {}
+      INTEGER_RULES.fetch(board, []).each do |key|
+        val = hash[key] || hash[key.to_sym]
+        next if val.blank?
+
+        unless val.is_a?(Integer) || val.to_s.match?(/\A\d+\z/)
+          raise ArgumentError, "#{key} non valido"
+        end
+        int_val = val.to_i
+        raise ArgumentError, "#{key} deve essere positivo" if int_val < 1
+      end
+    end
+
+    def self.validate(board_type, rules)
+      validate!(board_type, rules)
+      true
+    rescue ArgumentError
+      false
+    end
+  end
+end