Add Atlas Cloud image generation skill

[binyangzhu000-sudo]

Summary

• add an independently researched Atlas Cloud image-generation skill with dated catalog/schema evidence and production review guidance
• include a standard-library CLI that discovers live image models, validates the selected model schema, previews requests by default, submits at most one generation POST, and uses bounded prediction polling
• add guarded HTTPS image downloads, hidden evaluation criteria, 18 focused tests, and synchronized catalog counts

Validation

• uvx ruff check skills/providers/image-generation/atlas-cloud-image-generation/scripts/atlas_image.py skills/providers/image-generation/atlas-cloud-image-generation/tests/test_atlas_image.py
• uvx ruff format --check skills/providers/image-generation/atlas-cloud-image-generation/scripts/atlas_image.py skills/providers/image-generation/atlas-cloud-image-generation/tests/test_atlas_image.py
• python3 -m unittest discover -s skills/providers/image-generation/atlas-cloud-image-generation/tests -v (18 passed)
• python3 -m unittest discover -s tests -v (16 passed)
• python3 tools/package_skill.py skills/providers/image-generation/atlas-cloud-image-generation /tmp/atlas-cloud-image-generation-published --dry-run --list
• live Atlas smoke: google/nano-banana-2-lite/text-to-image completed and returned one valid 1024x1024 JPEG (53,779 bytes)

Safety notes

• dry-run is the default; paid submission requires both --submit and ATLASCLOUD_API_KEY
• generation POSTs are never retried; only prediction GET polling is bounded and retried
• credentials are never included in plans or logs