Move plugins to manifest, pin Docker version, add Makefile

- Add plugins.txt listing all plugins for reproducible installs
- Add Makefile with setup/start/stop/install-plugins targets
- Remove user/plugins/ from git tracking
- Pin Docker image to 1.7.49.5-ls244

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

plugins/automagic-images/vendor/paquettg/php-html-parser/composer.json

@@ -1,38 +0,0 @@
-{
-    "name": "paquettg/php-html-parser",
-    "type": "library",
-    "description": "An HTML DOM parser. It allows you to manipulate HTML. Find tags on an HTML page with selectors just like jQuery.",
-    "keywords": ["html", "dom", "parser"],
-    "homepage": "https://github.com/paquettg/php-html-parser",
-    "license": "MIT",
-    "authors": [
-        {
-            "name": "Gilles Paquette",
-            "email": "paquettg@gmail.com",
-            "homepage": "http://gillespaquette.ca"
-        }
-    ],
-    "require": {
-        "php": ">=7.2",
-        "ext-mbstring": "*",
-        "ext-zlib": "*",
-        "ext-curl": "*",
-        "paquettg/string-encode": "~1.0.0",
-        "php-http/httplug": "^2.1",
-        "guzzlehttp/guzzle": "^7.0",
-        "guzzlehttp/psr7": "^1.6",
-        "myclabs/php-enum": "^1.7"
-    },
-    "require-dev": {
-        "phpunit/phpunit": "^7.5.1",
-        "mockery/mockery": "^1.2",
-        "infection/infection": "^0.13.4",
-        "phan/phan": "^2.4",
-        "friendsofphp/php-cs-fixer": "^2.16"
-    },
-    "autoload": {
-        "psr-4": { 
-        	"PHPHtmlParser\\": "src/PHPHtmlParser"
-       	}
-    }
-}