v0.3.1: remove hover-triggered refresh -- it was the actual cause of the rate-limit bug

Live evidence right after 0.3.0 shipped: the log showed a repeating
success -> immediate 429 -> 120s backoff -> success -> immediate 429
cycle, matching "hover the icon a couple of times to check it" exactly.
Each hover fired an extra request on top of the timer (the 3s debounce
wasn't enough headroom), and those were what tripped the rate limit.
Hovering/clicking the tray icon no longer triggers any network request;
"Refresh now" remains the only manual trigger.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>