Add the Marble and Highlighter templates, completing the 13 Canva templates

Marble uses a flat-to-gradient band in place of the marble photo and bundles Lustria (OFL).
Both logo slots are opt-in. Quirk 13 documents a fontkit glyph-cache issue that the
tests work around with warm-up renders; the engine fix follows separately.

src/pdf/templates/cobalt/cobalt.test.tsx

@@ -64,12 +64,12 @@ async function colourAt(bytes: Uint8Array, points: Array<[number, number]>): Pro
 const near = (c: number[], hex: string, tol = 8) => [1, 3, 5].map((i) => parseInt(hex.slice(i, i + 2), 16)).every((w, i) => Math.abs(c[i] - w) <= tol);
 
 describe("registry, catalog and fonts", () => {
-  it("is registered last, as a standalone template with its thumbnail on disk", () => {
+  it("is registered before Marble and Highlighter, as a standalone template with its thumbnail on disk", () => {
     expect(getTemplate("cobalt-stripe")).toBe(cobaltStripe);
     expect(cobaltStripe.family).toBe("standalone");
     expect(catalogEntry("cobalt-stripe").name).toBe("Cobalt Stripe");
     expect(existsSync(path.join(process.cwd(), "public", cobaltStripe.thumbnail)), cobaltStripe.thumbnail).toBe(true);
-    expect(Object.keys(TEMPLATES).at(-1)).toBe("cobalt-stripe");
+    expect(Object.keys(TEMPLATES).slice(-3, -2)).toEqual(["cobalt-stripe"]);
     expect(TEMPLATE_CATALOG.map((e) => e.id)).toEqual(Object.keys(TEMPLATES));
   });