Implement ALTCHA captcha service with challenge generation and solution verification

- Added AltchaService class for managing ALTCHA captcha challenges and solutions.
- Created CaptchaController to handle API requests for generating challenges.
- Introduced CaptchaGuard for validating captcha solutions on public endpoints.
- Developed unit tests for AltchaService to ensure challenge creation and solution verification functionality.
- Implemented integration tests for the Captcha API endpoint and captcha bypass behavior when disabled.
- Added documentation for the Captcha API in the corresponding markdown file.

composer.lock

@@ -4,8 +4,55 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "e8ccf55959566a5f4e99d0965b1c988a",
+    "content-hash": "9cc89627fd2cff50402b8c5e93a9efee",
     "packages": [
+        {
+            "name": "altcha-org/altcha",
+            "version": "v2.0.3",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/altcha-org/altcha-lib-php.git",
+                "reference": "8b02ad2c9b82998613bac4d093517d457061cbbe"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/altcha-org/altcha-lib-php/zipball/8b02ad2c9b82998613bac4d093517d457061cbbe",
+                "reference": "8b02ad2c9b82998613bac4d093517d457061cbbe",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=8.1"
+            },
+            "require-dev": {
+                "friendsofphp/php-cs-fixer": "^3.72",
+                "phpstan/extension-installer": "^1.4",
+                "phpstan/phpstan": "^2.1",
+                "phpstan/phpstan-phpunit": "^2.0",
+                "phpunit/phpunit": "^10.5 || ^11.5"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "AltchaOrg\\Altcha\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Daniel Regeci",
+                    "email": "536331+ovx@users.noreply.github.com"
+                }
+            ],
+            "description": "A lightweight PHP library for creating and verifying ALTCHA challenges.",
+            "support": {
+                "issues": "https://github.com/altcha-org/altcha-lib-php/issues",
+                "source": "https://github.com/altcha-org/altcha-lib-php/tree/v2.0.3"
+            },
+            "time": "2026-07-02T16:36:58+00:00"
+        },
         {
             "name": "doctrine/collections",
             "version": "2.6.0",
@@ -9689,7 +9736,8 @@
     "platform": {
         "php": ">=8.2",
         "ext-ctype": "*",
-        "ext-iconv": "*"
+        "ext-iconv": "*",
+        "ext-soap": "*"
     },
     "platform-dev": {},
     "plugin-api-version": "2.9.0"