feat(ui): animated boot splash and loading screen

Show a Lottie-animated splash while the app bundle boots and dismiss it
once WebAppComponent initialises, plus a reusable mifosx-loading-screen
component with loading and error animations. lottie.min.js is served
from the lottie-web package instead of being vendored into src/assets.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/assets/styles/_loader.scss

@@ -6,53 +6,95 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+/* ==========================================================================
+   Modernized Loader Wrapper (Inspired by openMF/mifos-mobile)
+   Supports full-screen and embedded containers with smooth vector physics.
+   ========================================================================== */
 .loader-wrapper {
-  height: 100vh;
-  width: 100vw;
+  position: relative;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 100%;
+  min-height: 280px;
+  height: 100%;
+  background: transparent;
 
+  /* Modern orbital rings that replace legacy rigid triangles smoothly */
   .triangle {
-    width: 0;
-    height: 0;
-    border-style: solid;
     position: absolute;
-    animation: rotate 0.8s infinite 0.2s;
+    border-radius: 50%;
+    border-style: solid;
+    box-sizing: border-box;
+    transition: all 0.3s ease;
   }
 
   .bottom {
-    border-width: 0 90px 90px;
-    border-color: transparent transparent #1fb050;
-    bottom: calc(50% - 100px);
-    left: calc(50% - 90px);
+    width: 72px;
+    height: 72px;
+    border-width: 3px;
+    border-color: #2563eb transparent transparent;
+    animation: cbs-spin-ring 1.1s cubic-bezier(0.5, 0, 0.5, 1) infinite;
+    box-shadow: 0 0 16px rgb(37 99 235 / 35%);
   }
 
   .top {
-    border-width: 90px 90px 0;
-    border-color: #b4d575 transparent transparent;
-    top: calc(50% - 100px);
-    left: calc(50% - 90px);
+    width: 54px;
+    height: 54px;
+    border-width: 3px;
+    border-color: transparent transparent #0ea5e9;
+    animation: cbs-spin-ring 1.4s cubic-bezier(0.5, 0, 0.5, 1) infinite reverse;
+    box-shadow: 0 0 14px rgb(14 165 233 / 35%);
   }
 
   .left {
-    border-width: 90px 0 90px 90px;
-    border-color: transparent transparent transparent #1074b9;
-    top: calc(50% - 90px);
-    left: calc(50% - 100px);
+    width: 36px;
+    height: 36px;
+    border-width: 2.5px;
+    border-color: #10b981 transparent transparent;
+    animation: cbs-spin-ring 0.9s cubic-bezier(0.5, 0, 0.5, 1) infinite;
+    box-shadow: 0 0 10px rgb(16 185 129 / 35%);
   }
 
   .right {
-    border-width: 90px 90px 90px 0;
-    border-color: transparent #1daeec transparent transparent;
-    top: calc(50% - 90px);
-    right: calc(50% - 100px);
+    width: 18px;
+    height: 18px;
+    border-width: 2px;
+    border-color: transparent #38bdf8 transparent transparent;
+    animation: cbs-spin-ring 0.7s cubic-bezier(0.5, 0, 0.5, 1) infinite reverse;
   }
 
-  @keyframes rotate {
-    from {
-      transform: rotate(0deg);
-    }
-
-    to {
-      transform: rotate(360deg);
-    }
+  /* Optional central glowing core */
+  &::after {
+    content: '';
+    width: 8px;
+    height: 8px;
+    border-radius: 50%;
+    background: #38bdf8;
+    box-shadow: 0 0 12px #38bdf8;
+    animation: cbs-pulse-core 1.5s ease-in-out infinite;
+  }
+}
+
+@keyframes cbs-spin-ring {
+  from {
+    transform: rotate(0deg);
+  }
+
+  to {
+    transform: rotate(360deg);
+  }
+}
+
+@keyframes cbs-pulse-core {
+  0%,
+  100% {
+    transform: scale(0.85);
+    opacity: 0.6;
+  }
+
+  50% {
+    transform: scale(1.3);
+    opacity: 1;
   }
 }