feat(allocation): implement resource allocation feature

- Add AllocationController with CRUD + bulk endpoints
- Add AllocationValidationService for capacity/estimate validation
- Add AllocationMatrixService for optimized matrix queries
- Add AllocationPolicy for authorization
- Add AllocationResource for API responses
- Add frontend allocationService and matrix UI
- Add E2E tests for allocation matrix (20 tests)
- Add unit tests for validation service and policies
- Fix month format conversion (YYYY-MM to YYYY-MM-01)

backend/app/Utilities/WorkingDaysCalculator.php

@@ -7,9 +7,11 @@ use Carbon\CarbonPeriod;
 
 class WorkingDaysCalculator
 {
+    public const TIMEZONE = 'America/New_York';
+
     public static function calculate(string $month, array $holidays = []): int
     {
-        $start = Carbon::createFromFormat('Y-m', $month)->startOfMonth();
+        $start = Carbon::createFromFormat('Y-m', $month, self::TIMEZONE)->startOfMonth();
         $end = $start->copy()->endOfMonth();
 
         return self::getWorkingDaysInRange($start->toDateString(), $end->toDateString(), $holidays);
@@ -17,7 +19,10 @@ class WorkingDaysCalculator
 
     public static function getWorkingDaysInRange(string $start, string $end, array $holidays = []): int
     {
-        $period = CarbonPeriod::create(Carbon::create($start), Carbon::create($end));
+        $period = CarbonPeriod::create(
+            Carbon::create($start, self::TIMEZONE),
+            Carbon::create($end, self::TIMEZONE)
+        );
         $holidayLookup = array_flip($holidays);
         $workingDays = 0;
 
@@ -34,7 +39,7 @@ class WorkingDaysCalculator
 
     public static function isWorkingDay(string $date, array $holidays = []): bool
     {
-        $carbonDate = Carbon::create($date);
+        $carbonDate = Carbon::create($date, self::TIMEZONE);
 
         if ($carbonDate->isWeekend()) {
             return false;
@@ -46,4 +51,9 @@ class WorkingDaysCalculator
 
         return true;
     }
+
+    public static function isWeekend(string $date): bool
+    {
+        return Carbon::create($date, self::TIMEZONE)->isWeekend();
+    }
 }