feat: Add HTTP proxy for supported LLM nodes

[OlegIvaniv]

Summary

This PR adds HTTP proxy support to LangChain LLM nodes by implementing a new getHttpProxyAgent utility function that respects standard proxy environment variables (HTTP_PROXY, HTTPS_PROXY)

Changes include:

• Add new httpProxyAgent.ts utility to check for proxy environment variables
• Add comprehensive unit tests for the proxy agent functionality
• Add https-proxy-agent package dependency (v7.0.6)
• Implement proxy agent in LLM nodes including Anthropic, OpenAI, AWS Bedrock, Azure, Groq, and OpenRouter

Related Linear tickets, Github issues, and Community forum posts

closes #10901

Review / Merge checklist

• PR title and summary are descriptive. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.
• PR Labeled with release/backport (if the PR is an urgent fix that needs to be backported)

[cubic-dev-ai]

mrge reviewed 13 files and found no issues. Review PR in mrge.io.

[codecov]

Codecov Report

Attention: Patch coverage is 35.29412% with 11 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...chain/nodes/llms/LMChatOpenAi/LmChatOpenAi.node.ts	0.00%	2 Missing ⚠️
...des-langchain/nodes/llms/LMOpenAi/LmOpenAi.node.ts	0.00%	2 Missing ⚠️
...nodes/llms/LMChatAnthropic/LmChatAnthropic.node.ts	0.00%	1 Missing ⚠️
...des/llms/LmChatAwsBedrock/LmChatAwsBedrock.node.ts	0.00%	1 Missing ⚠️
...s/llms/LmChatAzureOpenAi/LmChatAzureOpenAi.node.ts	0.00%	1 Missing ⚠️
...n/nodes/llms/LmChatDeepSeek/LmChatDeepSeek.node.ts	0.00%	1 Missing ⚠️
...langchain/nodes/llms/LmChatGroq/LmChatGroq.node.ts	0.00%	1 Missing ⚠️
...des/llms/LmChatOpenRouter/LmChatOpenRouter.node.ts	0.00%	1 Missing ⚠️
...ain/nodes/llms/LmChatXAiGrok/LmChatXAiGrok.node.ts	0.00%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!

[ggozad]

Are we missing some providers? Ollama for example.

[OlegIvaniv]

Are we missing some providers? Ollama for example.
@ggozad Not all LLM proviers support custom httpAgent. I updated the order to prioritize HTTPS proxy. Can you have another look, pls?

[ggozad]

Awesome 🤩

[github-actions]

✅ All Cypress E2E specs passed

[kent-1]

Awesome, can you also make the same for Gemini please ??

As always good job guys.

[janober]

Got released with [email protected]