feat: replace openapi hashing system with /version

Apparently I didn't use my brain cells and rely on the /version
endpoint that Headscale has exposed since 0.26 (our lowest supported
version). Switching to that significantly simplifies the API surface.

package.json

@@ -15,7 +15,6 @@
     "docs:dev": "vitepress dev docs",
     "docs:build": "vitepress build docs",
     "docs:preview": "vitepress preview docs",
-    "gen:hashes": "tsx tests/generate-openapi-hashes.ts",
     "lint": "oxlint",
     "format": "oxfmt"
   },
@@ -32,7 +31,6 @@
     "@kubernetes/client-node": "^1.4.0",
     "@lezer/highlight": "^1.2.3",
     "@react-router/node": "^7.14.0",
-    "@readme/openapi-parser": "^6.0.1",
     "@uiw/react-codemirror": "4.25.9",
     "arktype": "^2.2.0",
     "clsx": "^2.1.1",
@@ -42,7 +40,6 @@
     "js-yaml": "^4.1.1",
     "lucide-react": "^1.8.0",
     "mime": "^4.1.0",
-    "openapi-types": "^12.1.3",
     "react": "19.2.5",
     "react-codemirror-merge": "4.25.9",
     "react-dom": "19.2.5",