Speed Test upload fix
Fixes upload measurement in the new Speed Test.
A bookkeeping bug introduced with 1.15.0's per-connection streams could zero out upload progress — the test would finish with "— Mbps" for upload while download measured fine. (URLSession task identifiers are only unique within one session; with one session per stream, the per-task progress counters collided.)
Also in this release, a failed measurement phase is now impossible to miss:
- A "▲ couldn't measure" tag appears right under the affected number.
- The reason — HTTP status or a stall — leads the "Why this verdict" list and is spelled out in the Test log.
- Upload gets the same refusal/stall diagnostics and anti-churn guards download already had.
Auto-updates via Sparkle; also on Homebrew: brew upgrade --cask mojo-pulse.