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/catalog.rb

@@ -0,0 +1,94 @@
+# frozen_string_literal: true
+
+module Sports
+  class Catalog
+    LEGACY_SPORT_MAP = {
+      "volleyball" => "pallavolo"
+    }.freeze
+
+    class << self
+      def all
+        @all ||= load_entries
+      end
+
+      def keys
+        all.keys
+      end
+
+      def find(key)
+        normalized = normalize_key(key)
+        entry = all[normalized]
+        raise KeyError, "Sport sconosciuto: #{key}" unless entry
+
+        entry.merge(key: normalized)
+      end
+
+      def find_optional(key)
+        normalized = normalize_key(key)
+        entry = all[normalized]
+        return nil unless entry
+
+        entry.merge(key: normalized)
+      end
+
+      def board_for(key)
+        find(key)[:board]
+      end
+
+      def overlay_for(key)
+        find(key)[:overlay]
+      end
+
+      def allowed_overlays_for(key)
+        find(key)[:allowed_overlays]
+      end
+
+      def default_rules_for(key)
+        deep_stringify_keys(find(key)[:default_rules] || {})
+      end
+
+      def normalize_key(key)
+        raw = key.to_s.strip
+        return "pallavolo" if raw.blank?
+
+        LEGACY_SPORT_MAP.fetch(raw, raw)
+      end
+
+      def as_api_list
+        all.map do |key, entry|
+          {
+            key: key,
+            label: entry[:label],
+            board: entry[:board],
+            overlay: entry[:overlay],
+            allowed_overlays: entry[:allowed_overlays],
+            default_rules: entry[:default_rules] || {}
+          }
+        end
+      end
+
+      private
+
+      def load_entries
+        path = Rails.root.join("config/sports.yml")
+        raw = YAML.safe_load(File.read(path), permitted_classes: [], aliases: true) || {}
+        raw.transform_keys(&:to_s).transform_values do |entry|
+          entry.deep_symbolize_keys
+        end.freeze
+      end
+
+      def deep_stringify_keys(value)
+        case value
+        when Hash
+          value.each_with_object({}) do |(k, v), h|
+            h[k.to_s] = deep_stringify_keys(v)
+          end
+        when Array
+          value.map { |v| deep_stringify_keys(v) }
+        else
+          value
+        end
+      end
+    end
+  end
+end