Bump version to 0.1.2 and add updater signing key

Add auto-update feature with Check for Update tray menu item

Fix usage data scraping reliability and null display

Fix the width of screenshot in the README.md

Update the readme with screenshot

Bump version to 0.1.1

Fix transparent window corners and improve text contrast

Fix Windows icon: replace PNG stub with proper multi-resolution ICO

Add cross-platform release workflow and update README

Initial commit for ClaudeMeter