feat(07-01): wire global schema.org Person + WebSite and sitemap sources

- nuxt.config.ts: register 'nuxt-schema-org' module + sitemap.sources=['/api/__sitemap__/urls']
- app/utils/seo-person.ts: KILLIAN_PERSON_ID + killianPerson (derived from siteConfig, email excluded)
- app/app.vue: useSchemaOrg([definePerson(killianPerson), defineWebSite({name, inLanguage})]) appended (D-12)
- Verified SSR: /fr emits JSON-LD Person @id=#killian + WebSite (curl, pas d'hydratation)

app/utils/seo-person.ts

@@ -0,0 +1,18 @@
+/**
+ * Global Person identity for schema.org (Killian Dal-Cin).
+ * Consumed by: app/app.vue (definePerson global) and app/pages/blog/[slug].vue (author/publisher @id ref).
+ * Derives URLs from siteConfig — single source of truth.
+ */
+import { siteConfig } from '~/data/site'
+
+export const KILLIAN_PERSON_ID = '#killian'
+
+export const killianPerson = {
+  '@id': KILLIAN_PERSON_ID,
+  name: "Killian' Dal-Cin",
+  url: siteConfig.url,
+  jobTitle: siteConfig.jobTitle,
+  sameAs: siteConfig.social
+    .filter((s) => s.name !== 'Email')
+    .map((s) => s.url),
+} as const