fix(clone): allow ee site clone onto a host with no existing sites

[mrrobot47]

Problem

ee site clone aborts with:

Warning: Encountered error while cloning site. Rolling back.
Error: Unable to get site list on @localhost

whenever the destination host has zero existing EasyEngine sites — making it impossible to clone the very first site onto a fresh/empty host. ee site sync hits the same misleading error.

Root cause

Cloner::site_exists() inspected stdout for the Error: No sites found! sentinel, but on an empty host ee site list calls \EE::error( 'No sites found!' ), which writes that message to stderr and exits 1. The special-case never matched, so execution fell through to the generic Unable to get site list throw.

It fails whenever the streams stay separate: a local source or destination, and ssh when ee isn't run from a terminal (ssh -t only allocates a pty when stdin is a tty, so automation such as EasyDash hits it on remote hosts too). From an interactive terminal, ssh -t's pty merges the remote stderr into stdout, which the old stdout match happened to catch.

Fix

• Match the sentinel against stderr . stdout (covers both the local separate-streams case and the ssh -t merged case), using strpos to tolerate a trailing newline / surrounding whitespace.
• Extract the check into is_no_sites_error(), gated on exit code 1 (the code \EE::error always exits with) so an unrelated non-zero failure can't be mistaken for "no sites" via a substring match.
• validate_parent_site_present_on_host() (reached on same-name --ssl=inherit clones) no longer runs foreach over null on an empty host. Only the "No sites found!" error counts as an empty host; any other unparseable ee site list result, including exit 0 with non-JSON output, now fails with Unable to get site list instead of being reported as "parent site not found".
• site_exists() now also fails with Unable to get site list when ee site list exits 0 with output that isn't a JSON list (e.g. shell-rc output or a PHP notice on stdout). Before, it reported the site as missing, so a clone onto an existing destination site tried to create it, failed, and the rollback then deleted the existing destination site.
• The parent-site check for same-name --ssl=inherit clones accepts the wildcard flag as an int. On PHP 8.1+ ee site info --format=json returns site_ssl_wildcard as 1, not '1', so the strict === '1' comparison never matched and these clones to another host always failed with "Parent site … not found", even when the parent had wildcard SSL. Both fields are now checked with empty().

Verification

• Empty host: ee site clone a.test b.test and ee site sync a.test b.test now fail with Unable to find 'a.test' on 'localhost' instead of Unable to get site list on @localhost. The same happens with a remote source when ee runs without a terminal. The pty-merged ssh -t output is still recognized.
• Clone onto an empty destination host gets past the existence check and runs ee site create there (before: Unable to get site list on user@host).
• ee site sync onto an empty destination still fails, because the destination site must exist; the error is now Unable to find '<site>' on '<host>'.
• --ssl=inherit same-name clone onto an empty host: "Parent site … not found" with no PHP warning; exit 0 with unparseable output gives Unable to get site list.
• With existing sites: a local clone, cloning onto an existing site (refused, destination untouched), sync --files, sync to a missing site, a clone from a remote source, and a disabled source all behave as before.
• Clone onto an existing destination site whose ssh session prints extra output before ee site list (exit 0): Unable to get site list on <host>, no ee site delete is run, and the destination site keeps working.
• --ssl=inherit same-name clone to another host whose parent has wildcard SSL: the parent is found and the clone goes on to ee site create … --ssl=inherit (before: "Parent site … not found").

Tested on Ubuntu 26.04 with EasyEngine 4.12.0 with local clones and syncs, and over real ssh to root@localhost: the empty-host case with and without a terminal, a clone from root@localhost onto the local host, and the destination with extra output in its ssh session. Because the test host is both source and destination, the clone onto an empty remote destination and the cross-host --ssl=inherit clone were exercised with ssh replaced by a local stand-in that runs the commands locally and replays the destination's recorded ee site list output.