Add Drupal headless stack with Next.js frontend

- Add Next.js frontend service (nextjs) with Dockerfile and source
- Update docker-compose.yml: image names, Drupal 11.3.3, nextjs service
- Add docker-compose.override.yml.disabled for dev hot-reload
- Add install-headless-modules.sh for OAuth/JSON:API module setup
- Add README.md with full setup and configuration guide
- Update nginx/Dockerfile and nginx.conf.template for cms. subdomain
- Update drupal/Dockerfile PHP-FPM build args
- Gitignore **/.vscode/ to prevent IDE workspace files from being tracked

drupal/nextjs/components/main-nav.tsx

@@ -0,0 +1,76 @@
+import type { DrupalMenuItem } from "next-drupal"
+import { MainNavClient } from "./main-nav-client"
+
+const drupalBaseUrl = process.env.NEXT_PUBLIC_DRUPAL_BASE_URL ?? ""
+
+interface RawMenuItem {
+  id: string
+  parent: string
+  title: string
+  url: string
+  enabled?: boolean
+  weight?: string | number
+}
+
+function buildMenuTree(
+  items: RawMenuItem[],
+  parentId: string
+): DrupalMenuItem[] {
+  return items
+    .filter((item) => (item.parent || "") === parentId && item.enabled !== false)
+    .sort((a, b) => Number(a.weight ?? 0) - Number(b.weight ?? 0))
+    .map((item) => {
+      const children = buildMenuTree(items, item.id)
+      return {
+        ...item,
+        items: children.length ? children : undefined,
+      } as DrupalMenuItem
+    })
+}
+
+const FALLBACK_MENU: DrupalMenuItem[] = [
+  {
+    id: "home",
+    title: "Home",
+    url: "/",
+    enabled: true,
+    items: undefined,
+  } as DrupalMenuItem,
+]
+
+async function getMainMenu(): Promise<DrupalMenuItem[]> {
+  if (!drupalBaseUrl) return FALLBACK_MENU
+
+  try {
+    const url = `${drupalBaseUrl.replace(/\/$/, "")}/jsonapi/menu_items/main`
+    const controller = new AbortController()
+    const timeoutId = setTimeout(() => controller.abort(), 5000)
+    const res = await fetch(url, {
+      headers: { Accept: "application/vnd.api+json" },
+      next: { revalidate: 60 },
+      signal: controller.signal,
+    })
+    clearTimeout(timeoutId)
+    if (!res.ok) {
+      if (res.status !== 404) {
+        console.warn(`[MainNav] Menu fetch returned ${res.status}, using fallback nav.`)
+      }
+      return FALLBACK_MENU
+    }
+
+    const json = await res.json()
+    const items: RawMenuItem[] = json.data ?? []
+
+    return buildMenuTree(items, "")
+  } catch (error) {
+    if ((error as Error).name !== "AbortError") {
+      console.warn("[MainNav] CMS unreachable, using fallback nav:", (error as Error).message)
+    }
+    return FALLBACK_MENU
+  }
+}
+
+export async function MainNav() {
+  const menuItems = await getMainMenu()
+  return <MainNavClient menuItems={menuItems} />
+}