feat(terminal): lazy-load targets and polish theme UI

Defer container loading with wire:init and a containersLoaded gate,
add autoStart/starting session state, extract a shared theme selector,
and restyle terminal headers, pickers, and fullscreen chrome. Cover the
new packaging and header behavior in feature tests.

app/Livewire/Project/Shared/Terminal.php

@@ -17,6 +17,8 @@ class Terminal extends Component
 
     public bool $isTerminalConnected = false;
 
+    public bool $autoStart = false;
+
     public string $variant = 'default';
 
     private function checkShellAvailability(Server $server, string $container): bool