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/Domain/SportTests.swift

@@ -124,22 +124,24 @@ struct SportTests {
 
     @Test("isInSeason boundary: first and last day of season month")
     func isInSeason_boundaryDays() {
-        let calendar = TestClock.calendar
+        // Production isInSeason uses Calendar.current to extract month.
+        // Use noon (hour: 12) so the date stays in the correct calendar day
+        // regardless of system timezone across the US.
 
         // MLB: First day of March (in season)
-        let marchFirst = calendar.date(from: DateComponents(year: 2026, month: 3, day: 1))!
+        let marchFirst = TestFixtures.date(year: 2026, month: 3, day: 1, hour: 12)
         #expect(Sport.mlb.isInSeason(for: marchFirst))
 
         // MLB: Last day of October (in season)
-        let octLast = calendar.date(from: DateComponents(year: 2026, month: 10, day: 31))!
+        let octLast = TestFixtures.date(year: 2026, month: 10, day: 31, hour: 12)
         #expect(Sport.mlb.isInSeason(for: octLast))
 
         // MLB: First day of November (out of season)
-        let novFirst = calendar.date(from: DateComponents(year: 2026, month: 11, day: 1))!
+        let novFirst = TestFixtures.date(year: 2026, month: 11, day: 1, hour: 12)
         #expect(!Sport.mlb.isInSeason(for: novFirst))
 
         // MLB: Last day of February (out of season)
-        let febLast = calendar.date(from: DateComponents(year: 2026, month: 2, day: 28))!
+        let febLast = TestFixtures.date(year: 2026, month: 2, day: 28, hour: 12)
         #expect(!Sport.mlb.isInSeason(for: febLast))
     }