Allow upload scripts to target a local API server instead of the remote
production server, enabling 32x+ concurrency for dramatically faster
full-cardset uploads (~30-45s vs ~2-3min for 800 cards).
- pd_cards/core/upload.py: add api_url param to upload_cards_to_s3(),
refresh_card_images(), and check_card_images()
- pd_cards/commands/upload.py: add --api-url CLI option to upload s3
- check_cards_and_upload.py: read PD_API_URL env var with prod fallback
- Update CLAUDE.md, CLI reference, and Phase 0 project plan docs
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
