feat: upgrade Symfony 7.4 -> 8.1, drop runtime/frankenphp-symfony

- All symfony/* constraints bumped 7.4.* -> 8.1.* (resolved to 8.1.2-8.1.6)
- Removed runtime/frankenphp-symfony: symfony/runtime 8.1 handles
  FrankenPHP worker mode natively via FrankenPhpWorkerRunner; deleted
  the extra.runtime class override so GenericRuntime auto-detects it
- phpunit 13.3.2, twig 3.28, otphp 11.5 ride along
- Deprecation sweep on 7.4 was clean (failOnDeprecation suite, zero hits)
- Verified: bin/console about boots on 8.1.6; 295 tests / 612 assertions
  green after the bump

composer.json

@@ -8,18 +8,17 @@
         "ext-ctype": "*",
         "ext-iconv": "*",
         "bacon/bacon-qr-code": "^3.1.1",
-        "runtime/frankenphp-symfony": "^1.0.0",
         "spomky-labs/otphp": "^11.4.2",
-        "symfony/cache": "7.4.*",
-        "symfony/console": "7.4.*",
+        "symfony/cache": "8.1.*",
+        "symfony/console": "8.1.*",
         "symfony/flex": "^2.11",
-        "symfony/framework-bundle": "7.4.*",
-        "symfony/mime": "7.4.*",
-        "symfony/rate-limiter": "7.4.*",
-        "symfony/runtime": "7.4.*",
-        "symfony/twig-bundle": "7.4.*",
-        "symfony/uid": "7.4.*",
-        "symfony/yaml": "7.4.*"
+        "symfony/framework-bundle": "8.1.*",
+        "symfony/mime": "8.1.*",
+        "symfony/rate-limiter": "8.1.*",
+        "symfony/runtime": "8.1.*",
+        "symfony/twig-bundle": "8.1.*",
+        "symfony/uid": "8.1.*",
+        "symfony/yaml": "8.1.*"
     },
     "config": {
         "allow-plugins": {
@@ -66,18 +65,15 @@
         "symfony/symfony": "*"
     },
     "extra": {
-        "runtime": {
-            "class": "Runtime\\FrankenPhpSymfony\\Runtime"
-        },
         "symfony": {
             "allow-contrib": false,
-            "require": "7.4.*"
+            "require": "8.1.*"
         }
     },
     "require-dev": {
         "friendsofphp/php-cs-fixer": "*",
         "phpunit/phpunit": "^13.2",
-        "symfony/browser-kit": "7.4.*",
-        "symfony/css-selector": "7.4.*"
+        "symfony/browser-kit": "8.1.*",
+        "symfony/css-selector": "8.1.*"
     }
 }