Bufferbloat tab fix

Fixes the Bufferbloat tab staying empty in Network Health.

The passive bufferbloat measurement only counted your Mac as "under load" past roughly 100 Mbps of your own traffic — so on most days, no samples ever qualified and the Bloat tab said "Collecting…" forever. Now a video call, a stream, or a backup counts (down > 8 Mbps or up > 2 Mbps), and the tab fills in from normal life. The degradation alarm still requires genuinely heavy queueing before it says anything.

Also in this release:

• The Bloat chart plots every Speed Test's measured latency-under-load as dots, so the tab shows real history even before passive samples accumulate — and its panel separates "Passive" from "Speed tests".
• When bloat truly has nothing to show, the tab now says why ("needs load to measure") instead of a generic "Collecting…".
• Fixed the live stats row wrapping when traffic units got long.

Auto-updates via Sparkle; also on Homebrew: brew upgrade --cask mojo-pulse.