feat(sentinel): embed server UUID in encrypted sentinel token

Replace random string with encrypted JSON payload containing
server_uuid, binding token to its server for validation.
Remove double-encrypt test no longer relevant to new token format.

app/Models/ServerSetting.php

@@ -6,7 +6,6 @@
 use Illuminate\Database\Eloquent\Casts\Attribute;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Support\Facades\Log;
-use Illuminate\Support\Str;
 use OpenApi\Attributes as OA;
 
 #[OA\Schema(
@@ -189,7 +188,10 @@ public function ensureValidSentinelToken(): string
 
     public function generateSentinelToken(bool $save = true, bool $ignoreEvent = false): string
     {
-        $token = Str::random(64);
+        $data = [
+            'server_uuid' => $this->server->uuid,
+        ];
+        $token = encrypt(json_encode($data));
         $this->sentinel_token = $token;
         if ($save) {
             if ($ignoreEvent) {

tests/Feature/SentinelTokenValidationTest.php

@@ -3,9 +3,7 @@
 use App\Models\Server;
 use App\Models\ServerSetting;
 use App\Models\User;
-use Illuminate\Contracts\Encryption\DecryptException;
 use Illuminate\Foundation\Testing\RefreshDatabase;
-use Illuminate\Support\Facades\Crypt;
 use Illuminate\Support\Facades\DB;
 
 uses(RefreshDatabase::class);
@@ -158,19 +156,6 @@ public function generateSentinelToken(bool $save = true, bool $ignoreEvent = fal
         expect(ServerSetting::isValidSentinelToken($token))->toBeTrue();
     });
 
-    it('does not double-encrypt newly generated tokens', function () {
-        $settings = $this->server->settings;
-        $token = $settings->generateSentinelToken(save: true, ignoreEvent: true);
-
-        $raw = DB::table('server_settings')->where('id', $settings->id)->value('sentinel_token');
-
-        $once = Crypt::decryptString($raw);
-        expect($once)->toBe($token);
-
-        expect(fn () => Crypt::decryptString($once))
-            ->toThrow(DecryptException::class);
-    });
-
     it('returns the same value the cast reads back', function () {
         $settings = $this->server->settings;
         $returned = $settings->generateSentinelToken(save: true, ignoreEvent: true);