Keep realtime stats test in sync with snapshot

[UfukNode]

This fixes the realtime stats browser test after the checked-in snapshot moved forward.

The test was still asserting the old task totals and daily task label, so node --test tests/realtime-stats.test.js failed on the current main data:

2207 !== 1822

Instead of baking the snapshot numbers into the test, this reads the expected task fields from data/realtime-stats.json. That keeps the test focused on parsing and formatting behavior while still letting the scheduled stats snapshot change over time.

Checked locally:

python3 -m unittest discover -s tests
python3 -m py_compile scripts/*.py tests/*.py
python3 -m json.tool data/realtime-stats.json >/dev/null
node --check realtime-stats.js
node --test tests/realtime-stats.test.js