Split the single-model and bulk context menu actions into 'Download
Missing Example Images' (regular endpoint, skips already-processed
models) and 'Re-process Example Images' (force endpoint, retries
failed models).
- start_download accepts model_hashes so a selected subset can be
processed with the progress-aware skip logic; explicitly targeted
models bypass the failed/processed model-level guards so per-image
gaps are filled
- pre-download existence check in the processor skips network requests
for image files already on disk across all download paths
- force download retries previously failed models and clears their
failed status on success
- add i18n keys for the new menu items across all locales
When Civitai returns 429 (Too Many Requests) during example image
downloads, the previous behavior treated all failures identically and
permanently removed the corresponding images from model metadata —
making them impossible to retry.
This commit adds:
- 429 detection + Retry-After header parsing in download_to_memory
- Exponential backoff retry (up to 3 attempts) in
download_model_images_with_tracking
- Separate tracking of rate-limited vs permanently failed URLs
- rate_limited_models progress tracking persisted to disk
- Rate-limited models are NOT added to failed_models/processed_models
so they are automatically retried on subsequent download runs
- Force mode clears failed_models when rate-limited images exist
