test(cli): canonicalize tmpDir with realpathSync for macOS

The new "writes a flat local config and returns the global project
identity" test failed on macOS because os.tmpdir() returns /var/... while
the project path stored in the global registry is canonicalized to
/private/var/... by registerProjectInGlobalConfig and loadConfig. Wrap
the comparison operand in realpathSync to match the prior art in the
PR's own integration test (cli-first-run-config.integration.test.ts:31).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/cli/__tests__/commands/start.test.ts

@@ -2429,7 +2429,7 @@ describe("start command — autoCreateConfig", () => {
     expect(projectIds).toHaveLength(1);
     expect(config.configPath).toBe(configPath);
     expect(Object.keys(config.projects)).toEqual(projectIds);
-    expect(config.projects[projectIds[0]!]!.path).toBe(tmpDir);
+    expect(config.projects[projectIds[0]!]!.path).toBe(realpathSync(tmpDir));
   });
 
   it("removes the flat local config when global registration fails", async () => {