Drop transformers, matplotlib, geopy, and diskcache (~560MB) from
dependencies — none are imported in the codebase. Replace single-stage
poetry-based Docker build with a two-stage pip-based build: builder
stage installs into a venv from an exported requirements.txt, runtime
stage copies only the venv and app code. Eliminates poetry from the
image (fixes ARM segfaults) and removes ~200MB of build tools from
the final image.
