feat(api): add llms.txt and llms-full.txt endpoints

Serve LLM-friendly documentation at /llms.txt (index) and
/llms-full.txt (full API docs as markdown). Generated from the
OpenAPI spec at startup.

apps/api/package.json

@@ -26,6 +26,7 @@
     "drizzle-orm": "^0.38.0",
     "exif-reader": "^2.0.3",
     "fastify": "^5.2.0",
+    "js-yaml": "^4.1.1",
     "jsqr": "^1.4.0",
     "p-queue": "^9.1.0",
     "pdfkit": "^0.18.0",
@@ -38,6 +39,7 @@
   "devDependencies": {
     "@types/archiver": "^7.0.0",
     "@types/better-sqlite3": "^7.6.0",
+    "@types/js-yaml": "^4.0.9",
     "@types/node": "^22.0.0",
     "@types/pdfkit": "^0.17.5",
     "@types/potrace": "^2.1.5",