fix: 12 planning engine bugs + App Store preview export at 886x1920

Planning engine fixes (from adversarial code review):
- Bug #1: sortByLeisure tie-breaking uses totalDrivingHours
- Bug #2: allDates/calculateRestDays guard-let-break prevents infinite loop
- Bug #3: same-day trip no longer rejected (>= in dateRange guard)
- Bug #4: ScenarioD rationale shows game count not stop count
- Bug #5: ScenarioD departureDate advanced to next day after last game
- Bug #6: ScenarioC date range boundary uses <= instead of <
- Bug #7: DrivingConstraints clamps maxHoursPerDriverPerDay via max(1.0,...)
- Bug #8: effectiveTripDuration uses inclusive day counting (+1)
- Bug #9: TripWizardViewModel validates endDate >= startDate
- Bug #10: allDates() uses min/max instead of first/last for robustness
- Bug #12: arrivalBeforeGameStart accounts for game end time at departure
- Bug #15: ScenarioBPlanner replaces force unwraps with safe unwrapping

Tests: 16 regression test suites + updated existing test expectations
Marketing: Remotion canvas set to 886x1920 for App Store preview spec

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

SportsTime/Planning/Engine/ScenarioBPlanner.swift

@@ -316,16 +316,16 @@ final class ScenarioBPlanner: ScenarioPlanner {
         // First window: last selected game is on last day of window
         // Window end = lastGameDate + 1 day (to include the game)
         // Window start = end - duration days
-        let firstWindowEnd = Calendar.current.date(
+        guard let firstWindowEnd = Calendar.current.date(
             byAdding: .day,
             value: 1,
             to: lastGameDate
-        )!
-        let firstWindowStart = Calendar.current.date(
+        ) else { return [] }
+        guard let firstWindowStart = Calendar.current.date(
             byAdding: .day,
             value: -duration,
             to: firstWindowEnd
-        )!
+        ) else { return [] }
 
         // Last window: first selected game is on first day of window
         // Window start = firstGameDate
@@ -334,21 +334,22 @@ final class ScenarioBPlanner: ScenarioPlanner {
         // Slide from first window to last window
         var currentStart = firstWindowStart
         while currentStart <= lastWindowStart {
-            let windowEnd = Calendar.current.date(
+            guard let windowEnd = Calendar.current.date(
                 byAdding: .day,
                 value: duration,
                 to: currentStart
-            )!
+            ) else { break }
 
             let window = DateInterval(start: currentStart, end: windowEnd)
             dateRanges.append(window)
 
             // Slide forward one day
-            currentStart = Calendar.current.date(
+            guard let nextStart = Calendar.current.date(
                 byAdding: .day,
                 value: 1,
                 to: currentStart
-            )!
+            ) else { break }
+            currentStart = nextStart
         }
 
         return dateRanges