feat(aura): add Carbon Blue atmospheric background partial

views/partials/aura-bg.php

@@ -0,0 +1,36 @@
+<?php
+/**
+ * Aura Background Partial — Carbon Blue
+ *
+ * Renders three decorative layers (linear gradient, radial backlight, SVG
+ * grain) over a transparent container. The body carries `background-color:
+ * #100e0b`; do NOT set a background on this container or the blend modes
+ * will composite against the container instead of the page.
+ *
+ * All layers are aria-hidden and ignore pointer events. Content must sit
+ * inside a wrapper with `position: relative; z-index: 1`.
+ *
+ * @package KsPortfolio
+ */
+
+namespace KsPortfolio;
+
+$blur = isset( $blur ) && 'desktop' === $blur ? 'aura-layer-2--desktop' : 'aura-layer-2--mobile';
+?>
+<div class="aura-bg" aria-hidden="true">
+	<div class="aura-layer-1"></div>
+	<div class="aura-layer-2 <?php echo esc_attr( $blur ); ?>"></div>
+	<div class="aura-grain">
+		<svg width="100%" height="100%" xmlns="http://www.w3.org/2000/svg" aria-hidden="true">
+			<filter id="aura-grain-filter">
+				<feTurbulence type="fractalNoise" baseFrequency="0.7" numOctaves="4" stitchTiles="stitch" />
+				<feColorMatrix type="matrix"
+					values="0.181 0.608 0.061 0 0.075
+					        0.181 0.608 0.061 0 0.075
+					        0.181 0.608 0.061 0 0.075
+					        0     0     0     1 0" />
+			</filter>
+			<rect width="100%" height="100%" filter="url(#aura-grain-filter)" />
+		</svg>
+	</div>
+</div>