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/email/vendor/doctrine/lexer/UPGRADE.md

@@ -1,14 +0,0 @@
-Note about upgrading: Doctrine uses static and runtime mechanisms to raise
-awareness about deprecated code.
-
-- Use of `@deprecated` docblock that is detected by IDEs (like PHPStorm) or
-  Static Analysis tools (like Psalm, phpstan)
-- Use of our low-overhead runtime deprecation API, details:
-  https://github.com/doctrine/deprecations/
-
-# Upgrade to 2.0.0
-
-`AbstractLexer::glimpse()` and `AbstractLexer::peek()` now return
-instances of `Doctrine\Common\Lexer\Token`, which is an array-like class
-Using it as an array is deprecated in favor of using properties of that class.
-Using `count()` on it is deprecated with no replacement.