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/Features/Trip/RegionMapSelectorTests.swift

@@ -56,10 +56,10 @@ struct RegionMapSelectorTests {
         #expect(RegionMapSelector.regionForCoordinate(coord) == .central)
     }
 
-    @Test("Central: Chicago (-87.62)")
+    @Test("Central: Chicago (-87.62) — actually East by longitude boundary")
     func central_chicago() {
-        let coord = CLLocationCoordinate2D(latitude: 41.88, longitude: -89.0)
-        #expect(RegionMapSelector.regionForCoordinate(coord) == .central)
+        let coord = CLLocationCoordinate2D(latitude: 41.88, longitude: -87.6553)
+        #expect(RegionMapSelector.regionForCoordinate(coord) == .east)
     }
 
     @Test("Central: exactly at west boundary (-102)")