feat(ui): point help new-content indicator at the updated tabs and elements

- Replace timestamp comparison (help_last_viewed vs a hardcoded date) with
  a content-version marker (data-help-content-version) read from the
  rendered modal markup, so badge state always reflects the content
  actually served
- Only mark content as viewed when the modal is opened while it contains
  new content; opening a stale pre-upgrade page no longer suppresses the
  badge after a refresh
- Flag the Replay Tutorial button itself with a 'New' chip (hidden by
  default, one-time glow animation) and scroll it into view when
  revealed; tab-level dots now mark getting-started and shortcuts
  instead of documentation
- Translate help.newContentBadge into all 9 locales, reusing the
  established help.documentation.newBadge renderings
- Add HelpManager content-version unit tests (12 cases)

static/css/components/modal/help-modal.css

@@ -167,6 +167,29 @@
   box-shadow: var(--shadow-lg);
 }
 
+/* Replay Tutorial button: badge hidden until the button is flagged as new content */
+.replay-tutorial-btn .new-content-badge {
+  display: none;
+  background-color: rgba(255, 255, 255, 0.22);
+  color: #fff;
+  box-shadow: none;
+  margin-left: 2px;
+}
+
+.replay-tutorial-btn.has-new-content .new-content-badge {
+  display: inline-flex;
+}
+
+/* One-time attention pulse when the button is flagged as new content */
+@keyframes new-content-glow {
+  0% { box-shadow: 0 0 0 0 oklch(from var(--lora-accent) l c h / 55%); }
+  100% { box-shadow: 0 0 0 16px transparent; }
+}
+
+.replay-tutorial-btn.has-new-content {
+  animation: new-content-glow 1.2s ease-out 3;
+}
+
 /* Update video list styles */
 .video-list {
   display: flex;