Fix: Handle AWS ECS 10-service limit in describe_services

[vertti]

Problem

Clusters with more than 10 services were crashing with the error:
Error: An error occurred (InvalidParameterException) when calling the DescribeServices operation: service names can have at most 10 items.

AWS ECS describe_services API has a hard limit of 10 services per call, but the code was attempting to describe all services in a single request.

Solution

Implemented batching for describe_services calls to process services in groups of 10:

1. Added batch_items() utility function (src/lazy_ecs/core/utils.py)

   • Generic helper to split lists into fixed-size chunks
   • Reusable for other AWS API limits

2. Updated ServiceService.get_service_info() (src/lazy_ecs/features/service/service.py)

   • Batches service names into groups of 10
   • Makes multiple describe_services calls as needed
   • Aggregates results from all batches
   • Uses Pythonic nested list comprehension for clean implementation

3. Added comprehensive tests

   • test_batch_items_*: Tests for utility function with various edge cases
   • test_get_service_info_with_more_than_10_services: Verifies batching works correctly with 15 services
   • All existing tests continue to pass

Closes #37