fix(test): make the auth-detect fixtures platform-neutral

Both new suites assumed POSIX: one compared against a literal forward-slash path that join() builds with backslashes on Windows, and the other passed a hardcoded /tmp to mkdtempSync, which does not exist there. Six failures on windows-latest, none on macOS or Linux.

Author: lidge-jun

tests/claude-auth-detect.test.ts

@@ -121,8 +121,9 @@ test("claudeConfigDir honours CLAUDE_CONFIG_DIR", () => {
 // `os.homedir()` reads the OS user database and IGNORES a reassigned HOME, so a probe
 // against an isolated profile would silently read the real user's files instead.
 test("claudeConfigDir follows a reassigned HOME instead of the OS user database", () => {
-  expect(claudeConfigDir({ HOME: "/tmp/fake-home" })).toBe("/tmp/fake-home/.claude");
-  expect(claudeConfigDir({ USERPROFILE: "C:\\fake" })).toContain(".claude");
+  // `join` uses the platform separator, so compare against a joined path, not a literal.
+  expect(claudeConfigDir({ HOME: join("/tmp", "fake-home") })).toBe(join("/tmp", "fake-home", ".claude"));
+  expect(claudeConfigDir({ USERPROFILE: join("/tmp", "fake-profile") })).toBe(join("/tmp", "fake-profile", ".claude"));
 });
 
 // Same reason for ~/.claude.json: under CLAUDE_CONFIG_DIR it is that dir's SIBLING.

tests/claude-system-env-auto.test.ts

@@ -1,6 +1,8 @@
 import { afterEach, beforeEach, expect, spyOn, test } from "bun:test";
 import * as childProcess from "node:child_process";
 import * as fs from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
 import { injectSystemEnv } from "../src/server/system-env";
 import { PROXY_MARKER } from "../src/claude/auth-detect";
 import type { OcxConfig } from "../src/types";
@@ -52,7 +54,7 @@ beforeEach(() => {
   delete process.env.ANTHROPIC_API_KEY;
   delete process.env.ANTHROPIC_AUTH_TOKEN;
   // An empty profile dir + a HOME with no ~/.claude.json = detection "absent".
-  const empty = fs.mkdtempSync("/tmp/ocx-sysenv-");
+  const empty = fs.mkdtempSync(join(tmpdir(), "ocx-sysenv-"));
   process.env.CLAUDE_CONFIG_DIR = empty;
   process.env.HOME = empty;