feat(copilot): support separate Protobuf and Avro schema generation prompts

[ysfscream]

PR Checklist

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What is the current behavior?

When requesting encoding/decoding help for message formats like Protobuf and Avro, the system sometimes returns both formats together inconsistently. The output formatting is also inconsistent across different AI models, with some responses lacking proper Markdown code blocks and structure.

Issue Number

What is the new behavior?

• Separated Protobuf and Avro encoding/decoding into distinct system prompts
• Improved prompt instructions to enforce consistent Markdown formatting with proper code blocks
• Added constraints to ensure AI responses maintain consistent structure and format
• Optimized custom function return formats with explicit instructions for code block usage

Does this PR introduce a breaking change?

• Yes
• No

Specific Instructions

Please test with various encoding/decoding scenarios to ensure the AI properly separates Protobuf and Avro responses and consistently uses proper Markdown formatting with code blocks.

Other information