feat: add configurable provider init params

[4pmtong]

Related Issue

Closes #

Description

• Chat.is_cloud() also matches proxy.eigent.ai (was: only the
  literal eigent-proxy substring, which the real proxy host lacks)
• agent_model / mcp default api_version for cloud Azure so camel's
  AzureOpenAIModel doesn't raise "Must provide api_version"

Testing Evidence (REQUIRED)

• I have included human-verified testing evidence in this PR.
• This PR includes frontend/UI changes, and I attached screenshot(s) or screen recording(s).
• No frontend/UI changes in this PR.

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Contribution Guidelines Acknowledgement

• I have read and agree to the Eigent Contribution Guideline