CLI App Clear Updates

`ed app clear-updates`

Deletes the record of past update checks.

ed app clear-updates [--json]

Name	Type / values	Default	What it does
`--json`	flag	off	Emit JSON on stdout.

--json shape, where removed is how many checks were in the log before it went:

{
  "removed": 42
}

Examples:

ed app clear-updates
ed app clear-updates --json

Without --json it prints cleared 42 check(s). This is the clear button in the update schedule sheet. It counts the file, deletes it, and exits 0 whether or not there was anything to delete, reporting cleared 0 check(s) in the empty case.

It is the only destructive verb in this group and it takes no --yes, because there is nothing behind the log: the file is removed outright rather than moved to the Trash, and the checks it held are gone. Nothing else is touched, and neither process needs to be running.