feat(domain): add DynamicSport model for CloudKit-defined sports

Struct representing sports synced from CloudKit. Conforms to AnySport
protocol for interchangeable use with Sport enum in UI and planning.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

SportsTime/Core/Models/Domain/DynamicSport.swift

@@ -0,0 +1,50 @@
+//
+//  DynamicSport.swift
+//  SportsTime
+//
+//  Domain model for CloudKit-defined sports.
+//
+
+import SwiftUI
+
+/// A sport defined via CloudKit, as opposed to the hardcoded Sport enum.
+/// Conforms to AnySport for interchangeable use with Sport enum.
+nonisolated struct DynamicSport: Identifiable, Hashable, Codable, Sendable {
+    let id: String
+    let abbreviation: String
+    let displayName: String
+    let iconName: String
+    let colorHex: String
+    let seasonStartMonth: Int
+    let seasonEndMonth: Int
+
+    init(
+        id: String,
+        abbreviation: String,
+        displayName: String,
+        iconName: String,
+        colorHex: String,
+        seasonStartMonth: Int,
+        seasonEndMonth: Int
+    ) {
+        self.id = id
+        self.abbreviation = abbreviation
+        self.displayName = displayName
+        self.iconName = iconName
+        self.colorHex = colorHex
+        self.seasonStartMonth = seasonStartMonth
+        self.seasonEndMonth = seasonEndMonth
+    }
+}
+
+// MARK: - AnySport Conformance
+
+extension DynamicSport: AnySport {
+    var sportId: String { id }
+
+    var color: Color { Color(hex: colorHex) }
+
+    var seasonMonths: (start: Int, end: Int) {
+        (seasonStartMonth, seasonEndMonth)
+    }
+}