feat(cases): Reddit Posts Explorer e MinGW GCC Installer com resposta, desafio, implementacao, limites e fontes fixadas em commit

- textos reescritos a partir do codigo e do README dos repositorios publicos (SHA ff76e08 e bab64fc); remove afirmacoes que o codigo nao sustenta (SSG, rate limiting/cache, busca em tempo real, download assincrono, monitoramento)
- public/portfolio-data.json alinhado (descricao, tecnologias, recursos e selos)
- testes: cinco cases detalhados, limite sourced + escopo editorial, guardas contra afirmacoes sem fonte

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

app/cases/[slug]/page.test.tsx

@@ -209,7 +209,7 @@ it("renders the authorized detailed case in order with traceable sources", async
 });
 
 it("keeps the fallback concise and links its declared services", async () => {
-  const caseStudy = getCase("gcc-installer");
+  const caseStudy = getCase("sc-plus");
   expect(caseStudy.detail).toBeUndefined();
   const ui = await CasePage({
     params: Promise.resolve({ slug: caseStudy.id }),
@@ -222,7 +222,9 @@ it("keeps the fallback concise and links its declared services", async () => {
   for (const technology of caseStudy.stack) {
     expect(screen.getByText(technology)).toBeVisible();
   }
-  expect(screen.queryByRole("link", { name: "Abrir demonstração" })).toBeNull();
+  expect(
+    screen.getByRole("link", { name: "Abrir demonstração" }),
+  ).toHaveAttribute("href", caseStudy.demoUrl);
   expect(screen.getByRole("link", { name: "Ver código" })).toHaveAttribute(
     "href",
     caseStudy.githubUrl,