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/Services/CapacityService.php

@@ -287,6 +287,23 @@ class CapacityService
         return $entry;
     }
 
+    public function batchUpsertAvailability(array $updates, string $month): int
+    {
+        $count = 0;
+
+        foreach ($updates as $update) {
+            TeamMemberAvailability::updateOrCreate(
+                ['team_member_id' => $update['team_member_id'], 'date' => $update['date']],
+                ['availability' => $update['availability']]
+            );
+            $count++;
+        }
+
+        $this->forgetCapacityCacheForMonth($month);
+
+        return $count;
+    }
+
     /**
      * Create a CarbonPeriod for the given month.
      */