Move the use-case index onto Learn so the pilot stories stay reachable, and make share images resolve on the host that serves the page.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/pages/use-cases-completed-rule.test.jsx

@@ -69,6 +69,14 @@ describe("UseCaseCompletedRulePage", () => {
         screen.getByRole("heading", { name: fixture.title }),
       ).toBeInTheDocument();
       if (slug === "mutual-aid-colorado") {
+        expect(
+          screen.getByText(/political solidarity rather than charity/),
+        ).toBeInTheDocument();
+        expect(
+          screen.queryByText(/Food Not Bombs is not a charity/),
+        ).not.toBeInTheDocument();
+      }
+      if (slug === "food-not-bombs") {
         expect(
           screen.getByText(/Food Not Bombs is not a charity/),
         ).toBeInTheDocument();