chore(frontend): upgrade Bootswatch and Bootstrap SCSS to v5.3.3

- Upgraded Bootswatch SCSS source files across all 25 themes (dev/scss/bootswatch/) to v5.3.3
- Upgraded Bootstrap SCSS source files (dev/scss/bootstrap/) to v5.3.3 to match static/js/bootstrap.bundle.min.js
- Updated dev/scss/bootstrap-overrides.scss to import bootstrap/variables-dark
- Verified error-free LibSass compilation for all 26 themes (25 Bootswatch + bootstrap-orj)
- Recompiled static/css/wvc-main.min.css

dev/scss/bootstrap/_progress.scss

@@ -8,7 +8,8 @@
 }
 // scss-docs-end progress-keyframes
 
-.progress {
+.progress,
+.progress-stacked {
   // scss-docs-start progress-css-vars
   --#{$prefix}progress-height: #{$progress-height};
   @include rfs($progress-font-size, --#{$prefix}progress-font-size);
@@ -46,6 +47,14 @@
   background-size: var(--#{$prefix}progress-height) var(--#{$prefix}progress-height);
 }
 
+.progress-stacked > .progress {
+  overflow: visible;
+}
+
+.progress-stacked > .progress > .progress-bar {
+  width: 100%;
+}
+
 @if $enable-transitions {
   .progress-bar-animated {
     animation: $progress-bar-animation-timing progress-bar-stripes;