feat(07-04): add dynamic sitemap URL feed for bilingual blog articles

- Nitro route server/api/__sitemap__/urls.ts via defineSitemapEventHandler
- Queries blog_fr + blog_en with literal strings and event first-arg (Pitfalls 1 & 2)
- Filters draft=false (D-10, T-07-06 mitigation)
- lastmod = updated ?? date (D-09)
- Emits hreflang alternates fr/en/x-default for bilingual pairs, none for single-language (D-11)
- Feeds @nuxtjs/sitemap via sitemap.sources declared in 07-01

server/api/__sitemap__/urls.ts

@@ -0,0 +1,76 @@
+/**
+ * Dynamic sitemap URL feed for @nuxtjs/sitemap.
+ * Referenced via nuxt.config.ts > sitemap.sources: ['/api/__sitemap__/urls'].
+ * Emits /fr/blog/{slug} + /en/blog/{slug} with hreflang alternates for bilingual pairs.
+ * Excludes drafts (D-10). lastmod = updated ?? date (D-09). See Pitfalls 1, 2, 5, 6 in RESEARCH.
+ */
+import { queryCollection } from '@nuxt/content/server'
+import type { SitemapUrl } from '#sitemap/types'
+
+const SITE_URL = 'https://killiandalcin.fr'
+
+type BlogRow = {
+  path: string
+  date: string
+  updated?: string
+}
+
+export default defineSitemapEventHandler(async (event) => {
+  // Literal collection strings (Pitfall 2). Pass event first (Pitfall 1).
+  const [frArticles, enArticles] = await Promise.all([
+    queryCollection(event, 'blog_fr')
+      .where('draft', '=', false)
+      .order('date', 'DESC')
+      .select('path', 'date', 'updated')
+      .all() as unknown as Promise<BlogRow[]>,
+    queryCollection(event, 'blog_en')
+      .where('draft', '=', false)
+      .order('date', 'DESC')
+      .select('path', 'date', 'updated')
+      .all() as unknown as Promise<BlogRow[]>,
+  ])
+
+  // Build slug → { fr?, en? } index for pair detection (D-11)
+  const extractSlug = (p: string) => p.split('/').filter(Boolean).pop()!
+  const index = new Map<string, { fr?: BlogRow; en?: BlogRow }>()
+  for (const a of frArticles) {
+    const s = extractSlug(a.path)
+    const e = index.get(s) ?? {}
+    e.fr = a
+    index.set(s, e)
+  }
+  for (const a of enArticles) {
+    const s = extractSlug(a.path)
+    const e = index.get(s) ?? {}
+    e.en = a
+    index.set(s, e)
+  }
+
+  const urls: SitemapUrl[] = []
+  for (const [slug, pair] of index) {
+    const bilingual = !!(pair.fr && pair.en)
+    const alternatives = bilingual
+      ? [
+          { hreflang: 'fr', href: `${SITE_URL}/fr/blog/${slug}` },
+          { hreflang: 'en', href: `${SITE_URL}/en/blog/${slug}` },
+          { hreflang: 'x-default', href: `${SITE_URL}/fr/blog/${slug}` },
+        ]
+      : []
+
+    if (pair.fr) {
+      urls.push({
+        loc: `/fr/blog/${slug}`,
+        lastmod: pair.fr.updated ?? pair.fr.date,
+        alternatives,
+      })
+    }
+    if (pair.en) {
+      urls.push({
+        loc: `/en/blog/${slug}`,
+        lastmod: pair.en.updated ?? pair.en.date,
+        alternatives,
+      })
+    }
+  }
+  return urls
+})