add .gitignore — skip __pycache__ and the huge raw site/*/traces.json files (lives in bucket instead)

add build_data.py — data-build helper (run per-sweep to produce site/<sweep>/summary.json + traces.json)

viz: bigger fonts, desktop-only gate, benchmark toggle + info popover, dense details panel with M×H/M×D/H×D matrices

switch to bucket-backed traces: slim repo, multi-dataset toggle + loader

deploy eval viz (consolidated single traces.json, in-memory serving)

initial commit