Summary

• update the stale image downscale test to call the current ingest_image service API
• keep the existing assertion that the returned ratio matches the actual resized image width

Root cause

_downscale_image was moved out of app.api.routes before backend/tests/test_image_downscale.py was added, so full backend test collection failed on an import error before the suite could run.

Validation

• python -m pytest backend/tests/test_image_downscale.py -q -> 1 passed
• $env:DEVELOPMENT_MODE='1'; python -m pytest backend/tests -q -> 153 passed, 8 failed in existing backend/tests/test_store_load_errors.py Windows permission scenarios; the stale import/collection blocker is fixed
• corepack pnpm exec vitest run -> 6 files passed, 73 tests passed
• E2E_TEST_MODE=1 GOOGLE_API_KEY=mock corepack pnpm exec playwright test with local backend/frontend servers -> 19 passed

Code and PR drafted with Codex