fix(ci): 在 requirements-test.txt 添加 e2b-code-interpreter

上一笔 refactor 移除了 cube 子包的 lazy-import 隔离层，
`trpc_agent_sdk.code_executors.cube.*` 现在在模块顶部 eager
`import e2b_code_interpreter as e2b`。CI 的 requirements-test.txt
之前没有 pin 这个 wheel（仅在 pyproject 的 [cube] extra 里声明），
导致整个 tests/code_executors/cube/ 目录在 collection 阶段
ModuleNotFoundError 失败。这里把 e2b-code-interpreter 显式列入
测试依赖，使 CI 能正常采集并运行 cube 单测。

Assisted-by: Cursor:claude-opus-4.7
Co-authored-by: Cursor <cursoragent@cursor.com>

Author: leeyyi

requirements-test.txt

@@ -22,6 +22,13 @@ google-genai>=1.24.0
 rapidfuzz>=3.0.0
 docker
 
+# Test Cube/E2B code executor
+# Cube tests now `import e2b_code_interpreter` at the top of the cube
+# subpackage modules (the lazy-import seam was removed); without this
+# wheel the whole `tests/code_executors/cube/` tree fails at collection
+# time on CI. Mirrors the `[cube]` optional extra in pyproject.toml.
+e2b-code-interpreter>=2.0.0
+
 # Test Langfuse
 opentelemetry-sdk<2.0.0,>=1.28.0
 opentelemetry-exporter-otlp-proto-http<2.0.0,>=1.28.0