test(cli): update tests and snapshots for enableCompactToolOutput

- Update all UI snapshots to synchronize with the new 'compact' default and minor layout tweaks.
- Update legacy UI regression tests to explicitly disable 'enableCompactToolOutput' to verify boxed layout behavior (overflows, sticky headers).
- Refactor 'useGeminiStream.test.tsx' to resolve TypeErrors and use consistent mock settings supporting the new UI options.
- Fix EPERM failures by using 'os.tmpdir()' in a2a-server and CLI theme tests to resolve macOS Seatbelt issues.

packages/a2a-server/src/utils/testing_utils.ts

@@ -20,6 +20,8 @@ import {
 import { createMockMessageBus } from '@google/gemini-cli-core/src/test-utils/mock-message-bus.js';
 import type { Config, Storage } from '@google/gemini-cli-core';
 import { expect, vi } from 'vitest';
+import os from 'node:os';
+import path from 'node:path';
 
 export function createMockConfig(
   overrides: Partial<Config> = {},
@@ -43,8 +45,8 @@ export function createMockConfig(
     getCheckpointingEnabled: vi.fn().mockReturnValue(false),
     // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion
     storage: {
-      getProjectTempDir: () => '/tmp',
-      getProjectTempCheckpointsDir: () => '/tmp/checkpoints',
+      getProjectTempDir: () => os.tmpdir(),
+      getProjectTempCheckpointsDir: () => path.join(os.tmpdir(), 'checkpoints'),
     } as Storage,
     getTruncateToolOutputThreshold: () =>
       DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD,