fix(seeding): ensure root user joins root team

Create the root team before production seeding depends on it, reuse the
existing root team when creating root users, and cover the production seeder
flow with a feature test.

app/Models/User.php

@@ -98,8 +98,18 @@ class User extends Authenticatable implements SendsEmail
                 $team['id'] = 0;
                 $team['name'] = 'Root Team';
             }
+            $new_team = $user->id === 0 ? Team::find(0) : null;
+
+            if ($new_team !== null) {
+                $new_team->forceFill($team);
+                $new_team->save();
+
+                return;
+            }
+
             $new_team = (new Team)->forceFill($team);
             $new_team->save();
+
             $user->teams()->attach($new_team, ['role' => 'owner']);
         });