Rotator classification: reject element-bearing containers, non-destructive runtime

A progressively-growing feed panel (rows injected after cap tagging)
passed the rotator leaf guard - which only rejected containers with
CAPPED children - and the rotator runtime's textContent writes then
flattened 51 statically-emitted descendants to one text node. Three
layers: emission drops rotators whose IR target has element children;
the capture leaf guard rejects any element child (capped or not); the
DittoMotion runtime saves/restores cloned child nodes via
replaceChildren so even a misclassified rotator can't destroy structure.

425 tests pass (6 new), typecheck clean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

compiler/src/capture/motion.ts

@@ -482,8 +482,11 @@ export async function captureMotion(page: Page, opts?: { observeMs?: number; log
             const cap = el && (el as Element).getAttribute?.("data-cid-cap");
             if (!cap) continue;
             const elem = el as Element;
-            // only track small text-bearing elements (a rotating word/phrase, not a big block)
-            if (elem.querySelector("[data-cid-cap]")) continue; // has element children → not a leaf word
+            // only track small text-bearing elements (a rotating word/phrase, not a big block).
+            // Reject ANY element child, capped or not: rows injected at runtime (after cid-cap
+            // tagging, so uncapped) would otherwise defeat a capped-only check and let a
+            // multi-element panel pass as a "leaf word".
+            if (elem.firstElementChild) continue; // has element children → not a leaf word
             const txt = norm(elem.textContent || "");
             if (!txt || txt.length > 80) continue;
             const e = changes.get(cap) ?? { texts: [], times: [] };