feat: add solutions list/detail pages

- types: SolutionPageSummary/Detail
- services/solution.service.ts
- app/solutions: list + detail pages
- Header nav: add 解决方案 link

services/solution.service.ts

@@ -0,0 +1,26 @@
+import { fetchAPI } from "./api-client";
+import type {
+  SolutionPageDetail,
+  SolutionPageSummary,
+  WagtailListResponse,
+} from "@/types/wagtail";
+
+/** 获取解决方案列表。 */
+export async function getSolutionList(): Promise<SolutionPageSummary[]> {
+  const res = await fetchAPI<WagtailListResponse<SolutionPageSummary>>(
+    "/api/v2/pages/?type=solutions.SolutionPage&fields=industry,summary",
+    { tags: ["solution-list"] },
+  );
+  return res.items;
+}
+
+/** 根据 slug 获取解决方案详情。 */
+export async function getSolutionBySlug(
+  slug: string,
+): Promise<SolutionPageDetail | null> {
+  const res = await fetchAPI<WagtailListResponse<SolutionPageDetail>>(
+    `/api/v2/pages/?type=solutions.SolutionPage&slug=${encodeURIComponent(slug)}&fields=body,industry,summary&limit=1`,
+    { tags: [`solution:${slug}`] },
+  );
+  return res.items[0] ?? null;
+}