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/myclabs/php-enum/psalm.xml

@@ -1,35 +0,0 @@
-<?xml version="1.0"?>
-<psalm
-    totallyTyped="true"
-    resolveFromConfigFile="true"
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xmlns="https://getpsalm.org/schema/config"
-    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
->
-    <projectFiles>
-        <directory name="src" />
-        <directory name="static-analysis" />
-        <ignoreFiles>
-            <directory name="vendor" />
-            <directory name="src/PHPUnit" />
-        </ignoreFiles>
-    </projectFiles>
-
-    <issueHandlers>
-        <MixedAssignment errorLevel="info" />
-
-        <ImpureStaticProperty>
-            <!-- self::$... usages in Enum are used to populate an internal cache, and cause no side-effects -->
-            <errorLevel type="suppress">
-                <file name="src/Enum.php"/>
-            </errorLevel>
-        </ImpureStaticProperty>
-
-        <ImpureVariable>
-            <!-- $this usages in Enum point themselves to an immutable instance -->
-            <errorLevel type="suppress">
-                <file name="src/Enum.php"/>
-            </errorLevel>
-        </ImpureVariable>
-    </issueHandlers>
-</psalm>