feat: improve planning engine travel handling, itinerary reordering, and scenario planners

Add TravelInfo initializers and city normalization helpers to fix repeat
city-pair disambiguation. Improve drag-and-drop reordering with segment
index tracking and source-row-aware zone calculation. Enhance all five
scenario planners with better next-day departure handling and travel
segment placement. Add comprehensive tests across all planners.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

SportsTimeTests/Planning/ScenarioAPlannerTests.swift

@@ -220,6 +220,55 @@ struct ScenarioAPlannerTests {
         #expect(failure.reason == .noGamesInRange)
     }
 
+    @Test("plan: multiple must-stop cities are required without excluding other route games")
+    func plan_multipleMustStops_requireCoverageWithoutExclusiveFiltering() {
+        let startDate = Date()
+        let endDate = startDate.addingTimeInterval(86400 * 10)
+
+        let nycStadium = makeStadium(id: "nyc", city: "New York", coordinate: nycCoord)
+        let bostonStadium = makeStadium(id: "boston", city: "Boston", coordinate: bostonCoord)
+        let phillyStadium = makeStadium(id: "philly", city: "Philadelphia", coordinate: CLLocationCoordinate2D(latitude: 39.9526, longitude: -75.1652))
+
+        let nycGame = makeGame(id: "nyc-game", stadiumId: "nyc", dateTime: startDate.addingTimeInterval(86400 * 1))
+        let bostonGame = makeGame(id: "boston-game", stadiumId: "boston", dateTime: startDate.addingTimeInterval(86400 * 3))
+        let phillyGame = makeGame(id: "philly-game", stadiumId: "philly", dateTime: startDate.addingTimeInterval(86400 * 5))
+
+        let prefs = TripPreferences(
+            planningMode: .dateRange,
+            sports: [.mlb],
+            startDate: startDate,
+            endDate: endDate,
+            leisureLevel: .moderate,
+            mustStopLocations: [
+                LocationInput(name: "New York", coordinate: nycCoord),
+                LocationInput(name: "Boston", coordinate: bostonCoord)
+            ],
+            lodgingType: .hotel,
+            numberOfDrivers: 2
+        )
+
+        let request = PlanningRequest(
+            preferences: prefs,
+            availableGames: [nycGame, bostonGame, phillyGame],
+            teams: [:],
+            stadiums: ["nyc": nycStadium, "boston": bostonStadium, "philly": phillyStadium]
+        )
+
+        let result = planner.plan(request: request)
+
+        guard case .success(let options) = result else {
+            Issue.record("Expected success with two feasible must-stop cities")
+            return
+        }
+
+        #expect(!options.isEmpty)
+        for option in options {
+            let gameIds = Set(option.stops.flatMap { $0.games })
+            #expect(gameIds.contains("nyc-game"), "Each option should satisfy New York must-stop")
+            #expect(gameIds.contains("boston-game"), "Each option should satisfy Boston must-stop")
+        }
+    }
+
     // MARK: - Specification Tests: Successful Planning
 
     @Test("plan: single game in range returns success with one option")