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/ScenarioDPlannerTests.swift

@@ -272,6 +272,63 @@ struct ScenarioDPlannerTests {
         #expect(!options.isEmpty)
     }
 
+    @Test("plan: useHomeLocation with startLocation adds home start and end stops")
+    func plan_useHomeLocationWithStartLocation_addsHomeEndpoints() {
+        let startDate = Date()
+        let endDate = startDate.addingTimeInterval(86400 * 10)
+
+        let homeCoord = CLLocationCoordinate2D(latitude: 39.7392, longitude: -104.9903)  // Denver
+        let homeLocation = LocationInput(name: "Denver", coordinate: homeCoord)
+
+        let bostonStadium = makeStadium(id: "boston", city: "Boston", coordinate: bostonCoord)
+        let game = Game(
+            id: "team-game",
+            homeTeamId: "red-sox",
+            awayTeamId: "yankees",
+            stadiumId: "boston",
+            dateTime: startDate.addingTimeInterval(86400 * 3),
+            sport: .mlb,
+            season: "2026",
+            isPlayoff: false
+        )
+
+        let prefs = TripPreferences(
+            planningMode: .followTeam,
+            startLocation: homeLocation,
+            sports: [.mlb],
+            startDate: startDate,
+            endDate: endDate,
+            leisureLevel: .moderate,
+            lodgingType: .hotel,
+            numberOfDrivers: 2,
+            followTeamId: "yankees",
+            useHomeLocation: true
+        )
+
+        let request = PlanningRequest(
+            preferences: prefs,
+            availableGames: [game],
+            teams: [:],
+            stadiums: ["boston": bostonStadium]
+        )
+
+        let result = planner.plan(request: request)
+
+        guard case .success(let options) = result else {
+            Issue.record("Expected success with home endpoint enabled")
+            return
+        }
+
+        #expect(!options.isEmpty)
+
+        for option in options {
+            #expect(option.stops.first?.city == "Denver")
+            #expect(option.stops.last?.city == "Denver")
+            #expect(option.stops.first?.games.isEmpty == true)
+            #expect(option.stops.last?.games.isEmpty == true)
+        }
+    }
+
     // MARK: - Invariant Tests
 
     @Test("Invariant: all returned games have team as home or away")