ai-assistant: Add DeepSeek provider support

[wingerx]

Add DeepSeek provider support:

• package.json: Added the @langchain/deepseek dependency.
• src/config/modelConfig.ts: Added a DeepSeek provider configuration (API key + model selection: deepseek-chat, deepseek-reasoner).
• src/langchain/LangChainManager.ts: Added a deepseek provider branch that instantiates ChatDeepSeek with API key and model.
• src/utils/icons.ts: Added the ai-providers:deepseek icon for offline provider rendering.

[Copilot]

Pull request overview

This PR adds support for the DeepSeek AI provider to the AI Assistant plugin, enabling users to configure and use DeepSeek models (deepseek-chat and deepseek-reasoner) alongside existing providers.

Changes:

• Added @langchain/deepseek package dependency (version 1.0.8)
• Configured DeepSeek provider with API key and model selection options
• Integrated ChatDeepSeek into LangChainManager's model creation logic
• Added DeepSeek icon for UI rendering

Reviewed changes

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

File	Description
ai-assistant/package.json	Added @langchain/deepseek dependency
ai-assistant/src/config/modelConfig.ts	Added DeepSeek provider configuration with API key and model selection fields
ai-assistant/src/langchain/LangChainManager.ts	Added deepseek case in createModel method to instantiate ChatDeepSeek
ai-assistant/src/utils/icons.ts	Added deepseek icon definition to aiProviderIcons collection

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 5 changed files in this pull request and generated 1 comment.

Files not reviewed (1)

• ai-assistant/package-lock.json: Language not supported

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

The package-lock.json shows that @langchain/deepseek requires @langchain/openai version 1.2.4, which has caused an update from the specified ^1.1.2. Consider updating this version constraint to ^1.2.4 to explicitly reflect the minimum required version and ensure consistent dependency resolution.

Suggested change

	"@langchain/openai": "^1.1.2",
	"@langchain/openai": "^1.2.4",

[illume]

Thanks for those changes.

Can you please check the git commit messages match the git commit guidelines in the contributing guide?

There's a conflict now, can you please have a look?

[Copilot]

Pull request overview

Copilot reviewed 4 out of 5 changed files in this pull request and generated no new comments.

Files not reviewed (1)

• ai-assistant/package-lock.json: Language not supported

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.