feat: 添加凭证支持到模型服务，增强 API 密钥管理

[OhYee]

Change-Id: Idf3ecad27a33902fc017c9392e314b252944c7ab

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Fix bugs

Bug detail

模型服务在配置凭证情况下，未正确获取 api key

Pull request tasks

• Add test cases for the changes
• Passed the CI test

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• Update English documentation

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[Copilot]

Pull request overview

This PR fixes a bug where model services were not correctly retrieving API keys when credentials were configured. The fix adds logic to fetch the API key from the associated credential when it's not directly provided in the provider settings.

• Added credential-based API key retrieval in model_info() method
• Added comprehensive test coverage for model services using credentials (both sync and async)
• Removed unused ClientError import from test files

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
agentrun/model/model_service.py	Added logic to retrieve API key from credential when not set in provider settings
agentrun/model/__model_service_async_template.py	Added same credential-based API key retrieval logic for async template
tests/e2e/test_model.py	Added sync and async test cases for model services with credentials; removed unused import
tests/e2e/__test_model_async_template.py	Added async test case for model services with credentials; removed unused import

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[Copilot]

In an async test method, Credential.create() should be replaced with await Credential.create_async() to maintain consistency with the async pattern used elsewhere in the test (e.g., await ModelService.create_async(), await ms.delete_async(), await cr.delete_async()). Using synchronous calls in async methods can lead to blocking behavior and defeats the purpose of async testing.

[OhYee]

@copilot open a new pull request to apply changes based on this feedback

[Copilot]

@OhYee I've opened a new pull request, #6, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

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