docs(core): [SITE-04] document public utility contracts

docs/llms.manifest.json

@@ -8,7 +8,7 @@
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     {
       "file": "packages/artplayer-vitepress/docs/en/advanced/class.md",
-      "sha256Lf": "10fcd0380ec75f5ba6a2784e6d68b86ee797f8b4a1871f64856de684241c3f84"
+      "sha256Lf": "1b4754150147a338c56de9475dd90065b72279edac2d7a087b53afe017839e4e"
     },
     {
       "file": "packages/artplayer-vitepress/docs/en/advanced/event.md",
@@ -347,5 +347,5 @@
       "sha256Lf": "967db6e5026a2fd3cc24d8a04e5c78859f543d0c0f6d4f9599c103e4e93c9b29"
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-  "outputSha256Lf": "f8d02b6e51e04027f9c2d5211d6ff5a3b26c34e350ec2d8033cdbac41265fad3"
+  "outputSha256Lf": "3a06a8d0a1bae67c5e3a445555e1f413c8e8add91ab12598989d5f0e5fc30ac4"
 }