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.

app/server/headscale/api/resources/api-keys.ts

@@ -0,0 +1,25 @@
+import type { Key } from "~/types";
+
+import type { Capabilities } from "../capabilities";
+import type { Transport } from "../transport";
+
+export interface ApiKeyApi {
+  list(): Promise<Key[]>;
+}
+
+export function makeApiKeyApi(
+  transport: Transport,
+  _capabilities: Capabilities,
+  apiKey: string,
+): ApiKeyApi {
+  return {
+    list: async () => {
+      const { apiKeys } = await transport.request<{ apiKeys: Key[] }>({
+        method: "GET",
+        path: "v1/apikey",
+        apiKey,
+      });
+      return apiKeys;
+    },
+  };
+}