feat(docs): add docs link fallback and inline difficulty badge in changelog page

apps/docs/pages/changelog.astro

@@ -82,29 +82,23 @@ const description = "Every topic and review the campaign finished, newest first.
                 {r.problems.map((p) => (
                   <li class="flex items-baseline gap-3 text-base leading-relaxed text-muted-foreground">
                     <span class="select-none text-border" aria-hidden="true">—</span>
-                    <span class="min-w-0 flex-1">
+                    <span class="min-w-0">
                       <span class="mr-2 font-mono text-xs uppercase tracking-wide">{p.set}</span>
-                      <a class="text-foreground no-underline hover:underline" href={issueUrl(p.issue)}>
+                      {/* The problem's docs page; its issue only until it has one. */}
+                      <a class="text-foreground no-underline hover:underline" href={p.docs ?? issueUrl(p.issue)}>
                         {p.title}
                       </a>
-                      {p.docs && (
-                        <a class="ml-2 font-mono text-xs text-emerald-500 no-underline hover:underline" href={p.docs}>
-                          view →
-                        </a>
-                      )}
-                    </span>
-                    {/* Its own right-hand column, one width for all three, so the
-                        badges line up down the card instead of crowding the link. */}
                       {DIFFICULTY[p.difficulty] && (
                         <span
                           class:list={[
-                          "w-12 shrink-0 rounded-full border py-px text-center font-mono text-[11px] leading-4",
+                            "ml-2 inline-block rounded-full border px-2 py-px align-middle font-mono text-[11px] leading-4",
                             DIFFICULTY[p.difficulty]!.class,
                           ]}
                         >
                           {DIFFICULTY[p.difficulty]!.label}
                         </span>
                       )}
+                    </span>
                   </li>
                 ))}
               </ul>