feat: implement Qwen provider with AI SDK

[daniel-lxs]

Summary

Adds a new Qwen provider (distinct from Qwen Code) using the qwen-ai-provider-v5 package and AI SDK. Uses Alibaba Cloud's DashScope API.

Changes

• Add QwenHandler using AI SDK with streamText/generateText
• Add 14 Qwen models with proper configurations
• Add UI settings component with API key field
• Add 22 tests for the provider

Models included

• qwen-max, qwen-max-latest - Most capable model, best for complex reasoning
• qwen-plus, qwen-plus-latest - Balanced performance and cost (default)
• qwen-turbo, qwen-turbo-latest - Fastest and most cost-effective
• qwen2.5-72b/32b/14b/7b-instruct - Open models with strong performance
• qwen2.5-14b-instruct-1m - Extended 1M context window variant
• qwen3-235b-a22b - Largest Qwen 3 model with MoE architecture
• qwen-vl-max, qwen-vl-plus - Vision models supporting images

Testing

• 22 unit tests covering constructor, getModel, createMessage, completePrompt, and model variants
• All tests passing
• TypeScript compilation successful

Closes EXT-712

---

Important

Implements Qwen provider with AI SDK, adds 14 models, updates UI, and includes comprehensive testing.

• Behavior:
  • Implements QwenHandler using AI SDK with streamText and generateText functions.
  • Adds 14 Qwen models with specific configurations in qwen.ts.
  • Integrates Qwen provider into UI with API key field in ApiOptions.tsx.
• Testing:
  • Adds 22 unit tests for QwenHandler in qwen.spec.ts covering constructor, getModel, createMessage, completePrompt, and model variants.
• Misc:
  • Updates provider-settings.ts and index.ts to include Qwen provider.
  • Adds i18n support for Qwen API key in multiple language files.
  • Updates package.json to include qwen-ai-provider-v5 dependency.

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[roomote]

Rooviewer   See task on Roo Cloud

Reviewed latest changes adding Qwen translations. Found a duplicate key in the English locale file.

• Remove unused import QWEN_API_BASE_URL_CHINA in src/api/providers/qwen.ts
• Remove duplicate key getQwenApiKey in webview-ui/src/i18n/locales/en/settings.json

Previous reviews

• 22a9316: Review #1

_{Mention @roomote in a comment to request specific changes to this pull request or fix all unresolved issues.}

[roomote]

QWEN_API_BASE_URL_CHINA is imported but never used in this file. The handler only uses QWEN_API_BASE_URL as the default when options.qwenBaseUrl is not provided. Consider removing this unused import.

Suggested change

	import {
	qwenModels,
	qwenDefaultModelId,
	QWEN_API_BASE_URL,
	QWEN_API_BASE_URL_CHINA,
	type ModelInfo,
	} from "@roo-code/types"
	import {
	qwenModels,
	qwenDefaultModelId,
	QWEN_API_BASE_URL,
	type ModelInfo,
	} from "@roo-code/types"

_{Fix it with Roo Code or mention @roomote and request a fix.}

[roomote]

Duplicate key getQwenApiKey - the line above already defines this key. In JSON objects, duplicate keys cause the second value to overwrite the first. This line should be removed.

Suggested change

"getQwenApiKey": "Get Qwen API Key",

_{Fix it with Roo Code or mention @roomote and request a fix.}