PAP-2615: rename source-header productivity-review pill to "Under review"

UX feedback split the badge by role: on the source issue the linked pill
describes a state ("Under review"), while on the productivity-review issue
itself the static pill identifies the kind of issue ("Productivity review").
Tooltip and aria-label still surface the formal name on hover.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/components/ProductivityReviewBadge.tsx

@@ -49,10 +49,10 @@ export function ProductivityReviewBadge({
             "inline-flex items-center gap-1 rounded-full border border-amber-500/40 bg-amber-500/10 px-2 py-0.5 text-[10px] font-medium text-amber-700 dark:text-amber-300 shrink-0 hover:bg-amber-500/20 transition-colors",
             className,
           )}
-          aria-label={`Productivity review ${reviewIdentifier} (${label})`}
+          aria-label={`Under review · productivity review ${reviewIdentifier} (${label})`}
         >
           <Eye className="h-3 w-3" aria-hidden />
-          {hideLabel ? null : <span>Productivity review</span>}
+          {hideLabel ? null : <span>Under review</span>}
         </Link>
       </TooltipTrigger>
       <TooltipContent>

ui/storybook/stories/status-language.stories.tsx

@@ -473,9 +473,11 @@ function ProductivityReviewMatrix() {
         </div>
       </div>
       <p className="text-xs text-muted-foreground">
-        The amber pill links from the source issue header to the open productivity-review child. List rows
-        get a smaller eye glyph next to the status icon so operators can spot yellow tasks without the
-        clickable label. The review issue itself shows the same amber pill in static (non-link) form.
+        On the source issue header the amber pill reads <strong>Under review</strong> and links to the open
+        productivity-review child — describing the state the task is in. The productivity-review issue itself
+        carries a static <strong>Productivity review</strong> pill identifying what kind of issue it is.
+        List rows get a smaller eye glyph next to the status icon so operators can spot yellow tasks without
+        the clickable label.
       </p>
     </div>
   );