v1.0.1

Checking for updates no longer depends on GitHub's API rate limit. den checks on every
start, and without a token GitHub's API allows 60 requests an hour per IP, so an office, a VPN
exit or a CI fleet behind one address got HTTP 403 in the Updates pane.

🔄 Updates

• The check reads the release feed on github.com (latest.json of the latest release) and the
  download uses the release's files by their URLs: the route install.sh and install.ps1
  already take, with no API call and no rate limit. A public repository needs nothing
  configured: no token, no updates: block. den needs HTTPS access to github.com and to
  release-assets.githubusercontent.com; behind a proxy it honours HTTPS_PROXY.
• GITHUB_TOKEN still selects the releases API, which a private repository needs. A release
  without latest.json falls back to the API, and a fork whose github_api is on
  api.github.com reads the feed of its own repository. GitHub Enterprise and the S3 mirror
  work as before.
• A failed check says what to do: that den could not reach github.com (set HTTPS_PROXY), that
  the repository is private (set GITHUB_TOKEN), or that GitHub's rate limit was reached.
• The Updates pane's help (h) shows where releases are read from and what you need, and the
  Updates documentation and Help topic list the same requirements.