feat: add qwen-extension.json for Qwen Code compatibility

[Ojhaharsh]

Adds qwen-extension.json to enable installation via Qwen Code CLI while maintaining full backward compatibility with Gemini CLI.

Problem

When installing this extension using Qwen Code CLI:

qwen extensions install https://github.com/gemini-cli-extensions/conductor

The installation fails with:

Configuration file not found at ...\qwen-extension.json

This occurs because Qwen Code (a fork of Gemini CLI) expects qwen-extension.json as the extension manifest filename, whereas this repo only provides gemini-extension.json.

Solution

Added qwen-extension.json with identical content to gemini-extension.json. This change:

✅ Enables installation via Qwen Code CLI
✅ Maintains full backward compatibility with Gemini CLI (which continues to use gemini-extension.json)
✅ Introduces zero breaking changes — purely additive

Verification

✅ Tested locally on Windows:

qwen extensions install .
qwen extensions list

Output:

✓ conductor (0.1.0)

✅ No impact on existing functionality — Gemini CLI users remain unaffected and can continue using gemini extensions install as before.

Compatibility Note

Qwen Code and Gemini CLI share nearly identical extension schemas and loading logic. This change simply adds the filename variant (qwen-extension.json) expected by Qwen Code's extension loader, without modifying any behavior or configuration structure.

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Fixes: QwenLM/qwen-code#1621