Add signed-in usage sync and MIT license

[Everyseok]

What changed

• read live Codex account rate limits through the existing signed-in account/rateLimits/read session
• retain local session JSONL data as an offline and low-latency fallback
• keep the 5H and WEEK rows fixed, using an em dash when the account does not report a window
• refresh the README, reproduction prompt, changelog, and preview artwork
• release the project under the MIT License

Why

The original widget relied only on local session snapshots, so values could be stale and an unavailable 5-hour window stayed as N/A. The new reader uses the authenticated Codex account snapshot without copying or storing OAuth credentials, while preserving the local fallback.

Impact

Users get live account-backed usage when Codex CLI is signed in. Plans that do not expose a 300-minute window remain clearly marked rather than showing a fabricated percentage. The repository now has explicit MIT reuse terms.

Verification

• build.ps1
• authenticated account dump (plan=prolite, weekly window parsed)
• forced offline/local fallback dump
• project and SVG XML validation
• installed executable version 1.1.0.0
• visual taskbar verification