feat: add planning tips and grouped trip options sorting

- Add PlanningTips data model with 105 tips across 7 categories
- Wire random tips into HomeView (3 tips per session)
- Add TripOptionsGrouper for grouping by city/game count and mileage
- Update TripOptionsView with sectioned display when sorting
- Recommended and Best Efficiency remain flat lists

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

SportsTimeTests/PlanningTipsTests.swift

@@ -0,0 +1,38 @@
+//
+//  PlanningTipsTests.swift
+//  SportsTimeTests
+//
+
+import Testing
+@testable import SportsTime
+
+struct PlanningTipsTests {
+
+    @Test func allTipsHasAtLeast100Tips() {
+        #expect(PlanningTips.all.count >= 100)
+    }
+
+    @Test func randomReturnsRequestedCount() {
+        let tips = PlanningTips.random(3)
+        #expect(tips.count == 3)
+    }
+
+    @Test func randomReturnsUniqueIds() {
+        let tips = PlanningTips.random(5)
+        let uniqueIds = Set(tips.map { $0.id })
+        #expect(uniqueIds.count == 5)
+    }
+
+    @Test func eachTipHasNonEmptyFields() {
+        for tip in PlanningTips.all {
+            #expect(!tip.icon.isEmpty, "Tip should have icon")
+            #expect(!tip.title.isEmpty, "Tip should have title")
+            #expect(!tip.subtitle.isEmpty, "Tip should have subtitle")
+        }
+    }
+
+    @Test func randomWithCountGreaterThanAvailableReturnsAll() {
+        let tips = PlanningTips.random(1000)
+        #expect(tips.count == PlanningTips.all.count)
+    }
+}

SportsTimeTests/TripOptionsGroupingTests.swift

@@ -0,0 +1,95 @@
+//
+//  TripOptionsGroupingTests.swift
+//  SportsTimeTests
+//
+
+import Testing
+@testable import SportsTime
+
+struct TripOptionsGroupingTests {
+
+    // Helper to create mock ItineraryOption
+    private func makeOption(stops: [(city: String, games: [String])], totalMiles: Double = 500) -> ItineraryOption {
+        let tripStops = stops.map { stopData in
+            TripStop(
+                city: stopData.city,
+                state: "XX",
+                coordinate: .init(latitude: 0, longitude: 0),
+                games: stopData.games,
+                arrivalDate: Date(),
+                departureDate: Date(),
+                travelFromPrevious: nil
+            )
+        }
+        return ItineraryOption(
+            id: UUID().uuidString,
+            stops: tripStops,
+            totalDistanceMiles: totalMiles,
+            totalDrivingHours: totalMiles / 60,
+            score: 1.0
+        )
+    }
+
+    @Test func groupByCityCountDescending() {
+        let options = [
+            makeOption(stops: [("NYC", []), ("Boston", [])]),  // 2 cities
+            makeOption(stops: [("LA", []), ("SF", []), ("Seattle", [])]),  // 3 cities
+            makeOption(stops: [("Chicago", [])]),  // 1 city
+        ]
+
+        let grouped = TripOptionsGrouper.groupByCityCount(options, ascending: false)
+
+        #expect(grouped.count == 3)
+        #expect(grouped[0].header == "3 cities")
+        #expect(grouped[1].header == "2 cities")
+        #expect(grouped[2].header == "1 city")
+    }
+
+    @Test func groupByGameCountAscending() {
+        let options = [
+            makeOption(stops: [("NYC", ["g1", "g2", "g3"])]),  // 3 games
+            makeOption(stops: [("LA", ["g1"])]),  // 1 game
+            makeOption(stops: [("Chicago", ["g1", "g2"])]),  // 2 games
+        ]
+
+        let grouped = TripOptionsGrouper.groupByGameCount(options, ascending: true)
+
+        #expect(grouped.count == 3)
+        #expect(grouped[0].header == "1 game")
+        #expect(grouped[1].header == "2 games")
+        #expect(grouped[2].header == "3 games")
+    }
+
+    @Test func groupByMileageRangeDescending() {
+        let options = [
+            makeOption(stops: [("NYC", [])], totalMiles: 300),   // 0-500
+            makeOption(stops: [("LA", [])], totalMiles: 1200),   // 1000-1500
+            makeOption(stops: [("Chicago", [])], totalMiles: 2500),  // 2000+
+        ]
+
+        let grouped = TripOptionsGrouper.groupByMileageRange(options, ascending: false)
+
+        #expect(grouped[0].header == "2000+ mi")
+        #expect(grouped[1].header == "1000-1500 mi")
+        #expect(grouped[2].header == "0-500 mi")
+    }
+
+    @Test func groupByMileageRangeAscending() {
+        let options = [
+            makeOption(stops: [("NYC", [])], totalMiles: 300),
+            makeOption(stops: [("LA", [])], totalMiles: 1200),
+            makeOption(stops: [("Chicago", [])], totalMiles: 2500),
+        ]
+
+        let grouped = TripOptionsGrouper.groupByMileageRange(options, ascending: true)
+
+        #expect(grouped[0].header == "0-500 mi")
+        #expect(grouped[1].header == "1000-1500 mi")
+        #expect(grouped[2].header == "2000+ mi")
+    }
+
+    @Test func emptyOptionsReturnsEmptyGroups() {
+        let grouped = TripOptionsGrouper.groupByCityCount([], ascending: false)
+        #expect(grouped.isEmpty)
+    }
+}