Audit and fix 52 test correctness issues across 22 files

Systematic audit of 1,191 tests found tests written to pass rather than
verify correctness. Key fixes:

Infrastructure:
- TestClock: fixed timezone from .current to America/New_York (deterministic)
- TestFixtures: added 1.3x road routing factor to match production
- ItineraryTestHelpers: real per-city coordinates instead of hardcoded (40,-80)

Planning tests:
- Added missing Scenario E factory dispatch tests
- Tightened 12 loose assertions (>= 1 → == 8.0, > 0 → range checks)
- Fixed 4 no-op tests that accepted both success and failure
- Fixed wrong repeat-city invariant (was checking same-day, not different-day)
- Fixed tautological assertion in missing-stadium edge case

Services/Domain/Export tests:
- Replaced 4 placeholder tests (#expect(true)) with real assertions
- Fixed tautological assertions in POISearchServiceTests
- Fixed Chicago coordinate in RegionMapSelectorTests (-89 → -87.6553)
- Added sort order verification to ItineraryRowFlatteningTests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

SportsTimeTests/Planning/TripPlanningEngineTests.swift

@@ -32,7 +32,7 @@ struct TripPlanningEngineTests {
     func drivingConstraints_clampsNegativeDrivers() {
         let constraints = DrivingConstraints(numberOfDrivers: -5, maxHoursPerDriverPerDay: 8.0)
         #expect(constraints.numberOfDrivers == 1)
-        #expect(constraints.maxDailyDrivingHours >= 1.0)
+        #expect(constraints.maxDailyDrivingHours == 8.0)
     }
 
     @Test("DrivingConstraints: clamps zero hours to minimum")
@@ -89,9 +89,11 @@ struct TripPlanningEngineTests {
     func invariant_totalDriverHoursPositive() {
         let prefs1 = TripPreferences(numberOfDrivers: 1)
         #expect(prefs1.totalDriverHoursPerDay > 0)
+        #expect(prefs1.totalDriverHoursPerDay == 8.0)  // 1 driver × 8 hrs
 
         let prefs2 = TripPreferences(numberOfDrivers: 3, maxDrivingHoursPerDriver: 4)
         #expect(prefs2.totalDriverHoursPerDay > 0)
+        #expect(prefs2.totalDriverHoursPerDay == 12.0)  // 3 drivers × 4 hrs
     }
 
     @Test("Invariant: effectiveTripDuration >= 1")
@@ -102,6 +104,10 @@ struct TripPlanningEngineTests {
             let prefs = TripPreferences(tripDuration: duration)
             #expect(prefs.effectiveTripDuration >= 1)
         }
+
+        // Verify specific value for nil duration with default dates
+        let prefsNil = TripPreferences(tripDuration: nil)
+        #expect(prefsNil.effectiveTripDuration == 8)  // Default 7-day range = 8 days inclusive
     }
 
     // MARK: - Travel Segment Validation
@@ -189,7 +195,7 @@ struct TripPlanningEngineTests {
         }
     }
 
-    @Test("planTrip: invalid options are filtered out")
+    @Test("ItineraryOption.isValid: correctly validates segment count")
     func planTrip_invalidOptions_areFilteredOut() {
         // Create a valid ItineraryOption manually with wrong segment count
         let stop1 = ItineraryStop(