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/users.ts

@@ -0,0 +1,66 @@
+import type { User } from "~/types";
+
+import type { Capabilities } from "../capabilities";
+import type { Transport } from "../transport";
+
+export interface CreateUserOptions {
+  name: string;
+  email?: string;
+  displayName?: string;
+  pictureUrl?: string;
+}
+
+export interface ListUsersFilter {
+  id?: string;
+  name?: string;
+  email?: string;
+}
+
+export interface UserApi {
+  list(filter?: ListUsersFilter): Promise<User[]>;
+  create(opts: CreateUserOptions): Promise<User>;
+  delete(id: string): Promise<void>;
+  rename(id: string, newName: string): Promise<void>;
+}
+
+export function makeUserApi(
+  transport: Transport,
+  _capabilities: Capabilities,
+  apiKey: string,
+): UserApi {
+  return {
+    list: async (filter) => {
+      const { id, name, email } = filter ?? {};
+      const moreThanOneFilter = [id, name, email].filter((v) => v !== undefined).length > 1;
+      if (moreThanOneFilter) {
+        throw new Error("Only one of id, name, or email filters can be provided");
+      }
+      const { users } = await transport.request<{ users: User[] }>({
+        method: "GET",
+        path: "v1/user",
+        apiKey,
+        query: { id, name, email },
+      });
+      return users;
+    },
+    create: async ({ name, email, displayName, pictureUrl }) => {
+      const { user } = await transport.request<{ user: User }>({
+        method: "POST",
+        path: "v1/user",
+        apiKey,
+        body: { name, email, displayName, pictureUrl },
+      });
+      return user;
+    },
+    delete: async (id) => {
+      await transport.request({ method: "DELETE", path: `v1/user/${id}`, apiKey });
+    },
+    rename: async (id, newName) => {
+      await transport.request({
+        method: "POST",
+        path: `v1/user/${id}/rename/${encodeURIComponent(newName)}`,
+        apiKey,
+      });
+    },
+  };
+}