Add toast with option to open post after publishing in web UI (#25564)

app/javascript/styles/mastodon/components.scss

@@ -9077,3 +9077,62 @@ noscript {
     }
   }
 }
+
+.notification-list {
+  position: fixed;
+  bottom: 2rem;
+  inset-inline-start: 0;
+  z-index: 999;
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+}
+
+.notification-bar {
+  flex: 0 0 auto;
+  position: relative;
+  inset-inline-start: -100%;
+  width: auto;
+  padding: 15px;
+  margin: 0;
+  color: $primary-text-color;
+  background: rgba($black, 0.85);
+  backdrop-filter: blur(8px);
+  border: 1px solid rgba(lighten($ui-base-color, 4%), 0.85);
+  border-radius: 8px;
+  box-shadow: 0 10px 15px -3px rgba($base-shadow-color, 0.25),
+    0 4px 6px -4px rgba($base-shadow-color, 0.25);
+  cursor: default;
+  transition: 0.5s cubic-bezier(0.89, 0.01, 0.5, 1.1);
+  transform: translateZ(0);
+  font-size: 15px;
+  line-height: 21px;
+
+  &.notification-bar-active {
+    inset-inline-start: 1rem;
+  }
+}
+
+.notification-bar-title {
+  margin-inline-end: 5px;
+}
+
+.notification-bar-title,
+.notification-bar-action {
+  font-weight: 700;
+}
+
+.notification-bar-action {
+  text-transform: uppercase;
+  margin-inline-start: 10px;
+  cursor: pointer;
+  color: $highlight-text-color;
+  border-radius: 4px;
+  padding: 0 4px;
+
+  &:hover,
+  &:focus,
+  &:active {
+    background: rgba($ui-base-color, 0.85);
+  }
+}