Add manual staging ECS availability controls

[suguanYang]

Summary

• add a manually dispatched staging ECS workflow with status, start, and stop operations
• require a validated Ontos-AI GitHub approval URL before start/stop mutations and verify AWS account 107424103509
• start two healthy workers before the API, and stop the API before the accepted 30-minute worker drain
• report service counts/revisions, cold-start duration, and queued versus processing jobs without exposing runtime secrets
• document the operator procedure and keep automatic EventBridge schedules and extended-session controls out of this repository slice

This is the first Phase 1 repository slice from Ontos-AI/knowhere-api-infra#30. It does not create AWS resources or automatically dispatch AWS operations.

Verification

• uv run pytest deploy/ecs/test_manage_staging_workflow.py deploy/ecs/test_render_task_definitions.py -q
• uv run --group lint ruff check deploy/ecs/test_manage_staging_workflow.py deploy/ecs/render_task_definitions.py deploy/ecs/test_render_task_definitions.py
• uv run --group typecheck pyright deploy/ecs/test_manage_staging_workflow.py
• workflow YAML parse
• shell syntax check
• git diff --check