docs: update install instructions with Homebrew tap and notarization note

fix: disable code signing for CI test runs

chore: update gitignore to exclude zip and p12 release artifacts

ci: add sign, notarize, staple and homebrew tap update to release workflow

Add image

update xcuserstate

Make systray update constantyl

fix: reduce polling to 5min, back off 15min on 429 and clear token cache

fix: grant contents:write permission for release creation

fix: use macos-15 runner for Xcode 16 compatibility

Add CI/release workflows and download instructions

Initial commit: Claude Usage Systray