feat: add @sda/flair-elements-ui library

Angular 19+ standalone library with 61 components, 15 directives,
and 8 services for decorative visual effects, animations, and
micro-interactions.

Components include particle systems, flow fields, aurora effects,
tilt/holographic/spotlight cards, text effects, dividers, scroll
animations, generative art, celebrations, image treatments,
morphing shapes, terminal output, and pattern textures.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/fl-card-stack/fl-card-stack.component.scss

@@ -0,0 +1,30 @@
+:host {
+  display: block;
+  width: 100%;
+  height: 100%;
+  position: relative;
+}
+
+.fl-card-stack__container {
+  position: relative;
+  width: 100%;
+  height: 100%;
+
+  > * {
+    cursor: pointer;
+  }
+}
+
+:host.fl-card-stack--hover-expand {
+  .fl-card-stack__container > *:hover {
+    transform: translate(-50%, -50%) rotate(0deg) scale(1.05) !important;
+    z-index: 1000 !important;
+    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
+  }
+}
+
+:host.fl-card-stack--reduced-motion {
+  .fl-card-stack__container > * {
+    transition: none !important;
+  }
+}