v0.3.2: fix 0.3.1 freeze bug, add heartbeat logging, raise default poll interval to 5 min

0.3.1 (already tagged/released) has a real bug and should not be used:
removing the hover-refresh trigger also removed the TrayIconEvent handler
registration entirely instead of replacing it with a no-op, which caused
the GUI thread to wedge silently after the first OS-delivered tray event
-- confirmed live (one poll cycle logged, then 30+ minutes of silence
with the endpoint reachable the whole time). Restored the registration
as a genuine no-op, which is the exact plumbing proven stable across
0.2.0 and 0.3.0.

Also, based on live evidence today: even plain passive 60s polling with
zero manual/hover interaction was hitting HTTP 429 frequently, especially
after a day of heavy testing against the same account. Default poll
interval raised 60s -> 5 minutes (1 minute remains selectable, floor
unchanged). Added a heartbeat log on every successful poll (previously
silent) and menu-dispatch diagnostics, so "is this actually working" and
"did that click register" are never again pure guesswork from the log.

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