feat(domain): add AnySport protocol for unified sport handling

Defines protocol that both Sport enum and DynamicSport will conform to,
enabling interchangeable use in UI and planning engine.

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

SportsTime/Core/Models/Domain/AnySport.swift

@@ -0,0 +1,44 @@
+//
+//  AnySport.swift
+//  SportsTime
+//
+//  Protocol unifying Sport enum and DynamicSport for interchangeable use.
+//
+
+import SwiftUI
+
+/// Protocol that unifies Sport enum and DynamicSport
+/// Allows both to be used interchangeably in UI and planning engine.
+protocol AnySport: Identifiable, Hashable, Sendable {
+    /// Unique identifier string (e.g., "MLB", "xfl")
+    var sportId: String { get }
+
+    /// Display name for UI (e.g., "Major League Baseball", "XFL Football")
+    var displayName: String { get }
+
+    /// SF Symbol name for sport icon (e.g., "baseball.fill")
+    var iconName: String { get }
+
+    /// Theme color for this sport
+    var color: Color { get }
+
+    /// Season months (start and end, 1-12). End may be less than start for wrap-around seasons.
+    var seasonMonths: (start: Int, end: Int) { get }
+}
+
+extension AnySport {
+    /// Check if sport is in season for a given date
+    func isInSeason(for date: Date) -> Bool {
+        let calendar = Calendar.current
+        let month = calendar.component(.month, from: date)
+
+        let (start, end) = seasonMonths
+        if start <= end {
+            // Normal range (e.g., March to October)
+            return month >= start && month <= end
+        } else {
+            // Season wraps around year boundary (e.g., October to June)
+            return month >= start || month <= end
+        }
+    }
+}