Add Pagination Support for Large ECS Deployments

[vertti]

Problem

Users with large ECS deployments (100+ services, tasks, or clusters) experienced crashes with the error:
Error: A list with shortcuts supports a maximum of 36 choices as this the maximum number of keyboard shortcuts that are available. You provided 104 choices.

This was caused by questionary's 36-item keyboard shortcut limit, which was hit when:

1. Selecting from clusters with 100+ items
2. Selecting from services with 100+ items
3. Selecting actions for a service with 100+ tasks
4. Selecting task features with 10+ containers (6 actions per container)

Additionally, only the first 100 clusters/services/tasks were shown due to AWS API pagination not being implemented.

Solution

Implemented comprehensive pagination at both the AWS API and UI layers:

1. AWS API Pagination (paginate_aws_list())

• Created reusable helper function in core/utils.py
• Handles all AWS ECS list operations with type-safe operation names
• Applied to:
  • ClusterService.get_cluster_names() - now returns all clusters
  • ServiceService.get_services() - now returns all services
  • TaskService.get_tasks() - now returns all tasks
  • TaskService.get_task_history() - paginates both running and stopped tasks

2. UI Pagination (select_with_pagination())

• Created paginated selection component in core/navigation.py
• Features:
  • 25 items per page (configurable)
  • Next/Previous page navigation
  • Back and Exit buttons on every page
  • No keyboard shortcuts (avoids 36-item limit entirely)
• Applied to:
  • ClusterUI.select_cluster()
  • ServiceUI.select_service()
  • ServiceUI.select_service_action()
  • TaskUI.select_task()
  • TaskUI.select_task_feature()

3. Smart Threshold (30 items)

• Lists ≤30 items: use keyboard shortcuts for better UX
• Lists >30 items: use pagination to avoid crashes

Closes #16 and #17