fix(video): reclaim outDir on createRenderJob throw + hide empty 4th highlight

Final whole-branch review (Opus) triaged two FIX items from the SDD nits
ledger; the rest ship as-is.

- render.js: a synchronous throw from createRenderJob (post-mkdtemp, not
  awaited) left an empty outDir on disk — the outer catch only reclaimed
  extractDir. Reclaim outDir too when it exists, and correct the stale
  comment that claimed the out dir was never created.
- {vertical,square}.html: the 4th highlights <li> lived in the DOM hidden
  only by JS, so a no-JS / failed-script render would show an empty bullet.
  Start it style="display:none" and reveal on populate, so an unscripted
  render shows nothing instead.

Vitest smoke (release-announcement.test.js) 4/4 green; render.js syntax
checked. Python suite untouched by this fix (JS/HTML only).

motion/compositions/release-announcement/square.html

@@ -24,7 +24,7 @@
           <li class="highlights__item"><span class="highlights__tick"></span><span class="highlights__text">Fable-mode adopted fleet-wide</span></li>
           <li class="highlights__item"><span class="highlights__tick"></span><span class="highlights__text">FE/UX-UI design bar shipped</span></li>
           <li class="highlights__item"><span class="highlights__tick"></span><span class="highlights__text">Feature spotlight goes live on X</span></li>
-          <li class="highlights__item"><span class="highlights__tick"></span><span class="highlights__text"></span></li>
+          <li class="highlights__item" style="display:none"><span class="highlights__tick"></span><span class="highlights__text"></span></li>
         </ul>
       </div>
 
@@ -68,6 +68,7 @@
           if (!textEl) continue;
           if (i < highlights.length && highlights[i]) {
             textEl.textContent = String(highlights[i]);
+            items[i].style.display = "";
           } else {
             items[i].style.display = "none";
           }

motion/compositions/release-announcement/vertical.html

@@ -23,7 +23,7 @@
           <li class="highlights__item"><span class="highlights__tick"></span><span class="highlights__text">Fable-mode adopted fleet-wide</span></li>
           <li class="highlights__item"><span class="highlights__tick"></span><span class="highlights__text">FE/UX-UI design bar shipped</span></li>
           <li class="highlights__item"><span class="highlights__tick"></span><span class="highlights__text">Feature spotlight goes live on X</span></li>
-          <li class="highlights__item"><span class="highlights__tick"></span><span class="highlights__text"></span></li>
+          <li class="highlights__item" style="display:none"><span class="highlights__tick"></span><span class="highlights__text"></span></li>
         </ul>
       </div>
 
@@ -67,6 +67,7 @@
           if (!textEl) continue;
           if (i < highlights.length && highlights[i]) {
             textEl.textContent = String(highlights[i]);
+            items[i].style.display = "";
           } else {
             items[i].style.display = "none";
           }

video-renderer/render.js

@@ -127,9 +127,14 @@ export async function renderComposition({
         ]),
     };
   } catch (err) {
-    // On any pre-render failure the out dir was never created — only the
+    // Reclaim whatever temp dirs exist. outDir is created at the mkdtemp
-    // extract dir needs reclaiming. Re-throw so server.js maps it to 4xx/5xx.
+    // above, so a sync throw from createRenderJob (post-mkdtemp, not
+    // awaited) leaves an empty outDir behind — reclaim it too. Re-throw
+    // so server.js maps the failure to 4xx/5xx.
     await rm(extractDir, { recursive: true, force: true }).catch(() => {});
+    if (outDir) {
+      await rm(outDir, { recursive: true, force: true }).catch(() => {});
+    }
     throw err;
   }
 }