Add the Monolith and Cobalt Stripe templates

Standalone layouts for Canva templates 3 and 8, with the user's logo sized to the
placeholder box, a CapRule decor primitive, optional TableRows rule/heading options,
and a separate 1..45-row sweep test file.

src/pdf/templates/harness.sweep.ts

@@ -0,0 +1,25 @@
+import { describe, it } from "vitest";
+import { makeItems, prefsFor, PAGE_SIZE_IDS, renderFixture, type FixtureSpec } from "./harness";
+import { checkRendered } from "./harness.check";
+import { TEMPLATES } from "./registry";
+
+/** The standalone templates sweep in a file of their own, so vitest runs the two sweeps in parallel and the suite's wall time stays put. */
+export const STANDALONE_SWEEP = ["monolith", "cobalt-stripe"];
+
+/** 1..45 generated rows on A4 and Letter for the templates `pick` selects, each render through the harness checks. */
+export function describeSweep(pick: (id: string) => boolean): void {
+  describe("template harness: item-count sweep", () => {
+    for (const template of Object.values(TEMPLATES).filter((t) => pick(t.id))) {
+      for (const size of PAGE_SIZE_IDS) {
+        it(`${template.id}: 1..45 items on ${size}`, async () => {
+          const prefs = prefsFor(size, { templateId: template.id });
+          for (let count = 1; count <= 45; count++) {
+            const spec: FixtureSpec = { name: `sweep-${count}`, items: makeItems(count, true), invoice: { notes: count % 3 === 0 ? "Payment due within 30 days.\nThank you." : "" }, signature: count % 2 === 0 };
+            const r = await renderFixture(spec, prefs);
+            checkRendered(r, `${template.id}/items=${count}/${size} (${r.result.pages} pages)`);
+          }
+        });
+      }
+    }
+  });
+}