Add qwen model series and pricing

Related to #7

This pull request introduces the qwen model series, including their pricing details, to the model list in the application.

Adds a new data file: Creates src/data/qwen.ts to define the qwen model series, including qwen-long, qwen-turbo, qwen-plus, qwen-max, and several variations of qwen-max with their respective input and output pricing. All models are tagged under 'qwen-series' for easy identification.
Updates the platform list: Modifies src/data/platform.ts to import the newly created price_qwen from src/data/qwen.ts and adds the qwen model series to the platforms record, making it accessible within the application.

For more details, open the Copilot Workspace session.

small-tou / llm-price