[BUG] /plugin marketplace add rewrites gitee.com URLs to github.com

## Environment

• OS: Windows 11

## Steps to reproduce

1. Run /plugin marketplace add gitee.com/in-case-of-reed/skills

## Expected behavior
Clone from git@gitee.com:in-case-of-reed/skills.git

## Actual behavior
The command rewrites gitee.com to github.com and tries cloning from git@github.com, causing SSH auth failure:

Error: Failed to clone marketplace repository: SSH authentication failed.
Cloning into '...gitee-com-in-case-of-reed-skills'...
git@github.com: Permission denied (publickey).

## Additional context

• Manual clone via git@gitee.com works fine with configured SSH key
• Non-GitHub Git hosting URLs should not be rewritten to github.com