Sync 100MB limit and URL guidance from master

Sync 500MB upload limit and caption update from master

Sync URL input, gdown support, and memory optimizations from master

Fix: copy .streamlit/config.toml into Docker image to enable 10GB upload limit

Force rebuild: sync app.py fixes (skipped gate, reranked_scores_map, F2 honeypot count)

Initial HF Spaces deployment (orphan — no history)