Add seasonal effects for Pi Day, Pride, Rain, and Storm; enhance existing styles

- Introduced new CSS and JS files for Pi Day, Pride, Rain, and Storm effects.
- Updated existing seasonal styles (e.g., Halloween, Hearts, Resurrection) to improve performance with 'contain: layout paint'.
- Enhanced animations for seasonal effects, including adjustments to keyframes and element creation logic.
- Added configuration options for new effects in the main seasonals.js file.
- Updated test-site.html to include new seasonal options in the dropdown.

Jellyfin.Plugin.Seasonals/Web/pride.css

@@ -0,0 +1,32 @@
+.pride-container {
+    position: fixed;
+    top: 0;
+    left: 0;
+    width: 100vw;
+    height: 100vh;
+    pointer-events: none;
+    z-index: 9999;
+    overflow: hidden;
+    contain: layout paint;
+}
+
+
+.pride-heart {
+    position: absolute;
+    bottom: -50px;
+    animation: pride-rise ease-in infinite;
+    will-change: transform;
+}
+
+
+@keyframes pride-rise {
+    0% { transform: translateY(0) scale(0.8); opacity: 0; }
+    10% { opacity: 1; }
+    90% { opacity: 1; }
+    100% { transform: translateY(-115vh) scale(1.2); opacity: 0; }
+}
+
+/* Coloring the Jellyfin Header */
+.skinHeader.pride-header {
+    background: linear-gradient(90deg, #E40303, #FF8C00, #FFED00, #008026, #24408E, #732982) !important;
+}