The update check ran at most once a day and only printed a line after the
TUI exited. Now the registry is asked on every start (in the background,
3 s timeout, no cache) and the result reaches the TUI as a message.
With a newer release, the footer shows `q quit and update to vX` right of
help and quit, on a highlighted background (Theme.Highlight). `q` quits
and `main` installs the release once the terminal is restored, sharing
the code of `submarine update`; plain quit moves to `Q`, ctrl+c never
updates.
Drop LatestCached and CheckInterval. Add D27 and F58.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Releases are built locally (no runner) and uploaded to the Gitea generic
package registry. install.sh installs submarine plus a sub symlink;
`submarine update` replaces the binary after verifying its checksum.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>