v2.6.1 (Lyra): Welcome page, 404 handling, installatie docs, opschoning

Nieuwe features:
- Welkomstpagina bij lege content-map (nieuwe installatie detectie)
- 404-afhandeling binnen actieve theme via admin/static/404.html
- HTTP 404 status bij onbekende pagina's en missende taalprefix

Opschoning:
- Verwijderd: package.json, src/scss/, root .htaccess, themes/demo/
- Verwijderde vendor packages: php-mqtt/client, mustache/mustache
- AGENTS.md samengevoegd naar root, development/AGENTS.md verwijderd
- .gitignore opgeschoond (NPM/node_modules/.sass-cache verwijderd)

Documentatie:
- Installatie instructies toegevoegd aan README (Apache2/Nginx/PHP/composer)
- README en guide versie referenties bijgewerkt naar 2.6.1
- Release notes: docs/release-notes/v2.6.1.md

Tests:
- Pentest: 30/30 geslaagd, 0 vulnerabilities
- WCAG 2.1 AA: 25/25 geslaagd, 100% compliance
- Test scripts gebruiken Apache-URL i.p.v. localhost:8080

composer.lock

@@ -697,59 +697,6 @@
             },
             "time": "2026-01-13T17:56:03+00:00"
         },
-        {
-            "name": "mustache/mustache",
-            "version": "v3.0.0",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/bobthecow/mustache.php.git",
-                "reference": "176b6b21d68516dd5107a63ab71b0050e518b7a4"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/bobthecow/mustache.php/zipball/176b6b21d68516dd5107a63ab71b0050e518b7a4",
-                "reference": "176b6b21d68516dd5107a63ab71b0050e518b7a4",
-                "shasum": ""
-            },
-            "require": {
-                "php": ">=5.6"
-            },
-            "require-dev": {
-                "friendsofphp/php-cs-fixer": "~2.19.3",
-                "yoast/phpunit-polyfills": "^2.0"
-            },
-            "type": "library",
-            "autoload": {
-                "psr-4": {
-                    "Mustache\\": "src/"
-                },
-                "classmap": [
-                    "src/compat.php"
-                ]
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Justin Hileman",
-                    "email": "justin@justinhileman.info",
-                    "homepage": "http://justinhileman.com"
-                }
-            ],
-            "description": "A Mustache implementation in PHP.",
-            "homepage": "https://github.com/bobthecow/mustache.php",
-            "keywords": [
-                "mustache",
-                "templating"
-            ],
-            "support": {
-                "issues": "https://github.com/bobthecow/mustache.php/issues",
-                "source": "https://github.com/bobthecow/mustache.php/tree/v3.0.0"
-            },
-            "time": "2025-06-28T18:28:20+00:00"
-        },
         {
             "name": "myclabs/php-enum",
             "version": "1.8.5",
@@ -967,63 +914,6 @@
             },
             "time": "2025-10-31T00:45:47+00:00"
         },
-        {
-            "name": "php-mqtt/client",
-            "version": "v2.3.0",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/php-mqtt/client.git",
-                "reference": "3d141846753a0adee265680ae073cfb9030f2390"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/php-mqtt/client/zipball/3d141846753a0adee265680ae073cfb9030f2390",
-                "reference": "3d141846753a0adee265680ae073cfb9030f2390",
-                "shasum": ""
-            },
-            "require": {
-                "myclabs/php-enum": "^1.7",
-                "php": "^8.0",
-                "psr/log": "^1.1|^2.0|^3.0"
-            },
-            "require-dev": {
-                "phpunit/php-invoker": "^3.0",
-                "phpunit/phpunit": "^9.0",
-                "squizlabs/php_codesniffer": "^3.5"
-            },
-            "suggest": {
-                "ext-redis": "Required for the RedisRepository"
-            },
-            "type": "library",
-            "autoload": {
-                "psr-4": {
-                    "PhpMqtt\\Client\\": "src"
-                }
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Marvin Mall",
-                    "email": "marvin-mall@msn.com",
-                    "role": "developer"
-                }
-            ],
-            "description": "An MQTT client written in and for PHP.",
-            "keywords": [
-                "client",
-                "mqtt",
-                "publish",
-                "subscribe"
-            ],
-            "support": {
-                "issues": "https://github.com/php-mqtt/client/issues",
-                "source": "https://github.com/php-mqtt/client/tree/v2.3.0"
-            },
-            "time": "2025-09-30T17:53:34+00:00"
-        },
         {
             "name": "psr/event-dispatcher",
             "version": "1.0.0",
@@ -1837,10 +1727,10 @@
     "packages-dev": [],
     "aliases": [],
     "minimum-stability": "stable",
-    "stability-flags": {},
+    "stability-flags": [],
     "prefer-stable": false,
     "prefer-lowest": false,
-    "platform": {},
-    "platform-dev": {},
+    "platform": [],
+    "platform-dev": [],
     "plugin-api-version": "2.9.0"
 }