feat(indexnow): add IndexNow key file and trigger script

- public/15455d9f2c7b473bb04336055b792ec9.txt — ownership-ключ для Yandex/Bing
- scripts/indexnow.js — собирает URL из dist/sitemap-*.xml (fallback: remote sitemap-index), шлёт на yandex.com/indexnow и api.indexnow.org/indexnow
- package.json: npm run indexnow
- .gitea/workflows/deploy.yml: после успешного deploy чекаут + node + npm run indexnow (не блокирует пайплайн через || true)

package.json

@@ -11,7 +11,8 @@
     "build": "astro build",
     "preview": "astro preview",
     "astro": "astro",
-    "migrate": "node scripts/migrate-wp.mjs"
+    "migrate": "node scripts/migrate-wp.mjs",
+    "indexnow": "node scripts/indexnow.js"
   },
   "dependencies": {
     "@astrojs/rss": "^4.0.12",