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/string-encode/README.md

@@ -1,28 +0,0 @@
-String Encode
-==========================
-
-Version 1.0.1
-
-String Encode is a simple PHP wrapper package to facilitate the encoding of strings in different charsets.
-
-Install
--------
-
-This package can be found on [packagist](https://packagist.org/packages/paquettg/stringencode) and is best loaded using [composer](http://getcomposer.org/). It does require php 7.1 or higher, so keep that in consideration. 
-
-Usage
------
-
-This is a really simple package so there is not much to say about it. The following is just about the only usage for this package at the moment.
-
-```php
-use stringEncode\Encode;
-
-$str    = "Calendrier de l'avent façon Necta!"
-$encode = new Encode;
-$encode->detect($str);
-$newstr = $encode->convert($str);
-echo $newstr; // "Calendrier de l'avent façon Necta!" in UTF-8 encoding (default)
-```
-
-As you can see, it is a very simple encoding converter.