Improvements over 1.0.1:

• New "Check frequency" setting: choose how often the extension looks
for inactive tabs (1 minute minimum, 15 minutes default, presets in
the options page). The schedule updates on the fly.
• Cleanup now also runs when you switch tab, space or window (throttled
to once per 5 seconds). Zen Browser only exposes the active space's
tabs to extensions, so overdue tabs in another space are now closed
the moment you switch back to it.
• More robust tab collection on Zen: visible and hidden tabs are
queried with explicit filters and merged, working around Zen's
non-standard tabs.query behavior.
• Safer cleanup: tabs are closed one by one, so a tab closed manually
mid-cleanup no longer aborts the batch, and the restore list only
contains tabs that were actually closed.
• The popup now shows how many tabs are being watched and how many are
overdue.
• Notifications use a PNG icon; debug logs indicate what triggered each
check (schedule, activity or manual).