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/admin/themes/grav/scss/nucleus/_forms.scss

@@ -1,62 +0,0 @@
-fieldset {
-	border: 0;
-	padding: $content-padding;
-	margin: 0 0 $leading-margin 0;
-}
-
-input,
-label,
-select {
-	display: block;
-}
-
-label {
-	margin-bottom: $leading-margin / 4;
-
-	&.required:after {
-		content: "*";
-	}
-
-	abbr {
-		display: none;
-	}
-}
-
-textarea, #{$all-text-inputs}, select[multiple=multiple] {
-	@include transition(border-color);
-	border-radius: $core-border-radius;
-	padding: ($leading-margin / 4) ($leading-margin / 4);
-	width: 100%;
-
-	&:focus {
-		outline: none;
-	}
-}
-
-textarea {
-	resize: vertical;
-}
-
-input[type="checkbox"], input[type="radio"] {
-	display: inline;
-	margin-right: $leading-margin / 4;
-}
-
-input[type="file"] {
-	width: 100%;
-}
-
-select {
-	width: auto;
-	max-width: 100%;
-	margin-bottom: $leading-margin;
-}
-
-button,
-input[type="submit"] {
-	cursor: pointer;
-	user-select: none;
-	vertical-align: middle;
-	white-space: nowrap;
-	border: inherit;
-}