feat: add YAML export — serialize canvas nodes/edges to downloadable .yaml file

frontend/package-lock.json

@@ -13,12 +13,14 @@
         "@fontsource-variable/geist": "^5.2.8",
         "@fontsource-variable/inter": "^5.2.8",
         "@fontsource/jetbrains-mono": "^5.2.8",
+        "@types/js-yaml": "^4.0.9",
         "@xyflow/react": "^12.10.1",
         "axios": "^1.13.6",
         "class-variance-authority": "^0.7.1",
         "clsx": "^2.1.1",
         "dagre": "^0.8.5",
         "html-to-image": "^1.11.13",
+        "js-yaml": "^4.1.1",
         "next-themes": "^0.4.6",
         "react": "^19.2.0",
         "react-dom": "^19.2.0",
@@ -3008,6 +3010,12 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/js-yaml": {
+      "version": "4.0.9",
+      "resolved": "https://registry.npmjs.org/@types/js-yaml/-/js-yaml-4.0.9.tgz",
+      "integrity": "sha512-k4MGaQl5TGo/iipqb2UDG2UwjXziSWkh0uysQelTlJpX1qGlpUZYm8PnO4DxG1qBomtJUdYJ6qR6xdIah10JLg==",
+      "license": "MIT"
+    },
     "node_modules/@types/json-schema": {
       "version": "7.0.15",
       "resolved": "https://registry.npmjs.org/@types/json-schema/-/json-schema-7.0.15.tgz",