Make Git AI embedded skills compatible with Cursor, Amp, etc.

[acunniffe]

In the last version we released the prompt-analysis skill https://github.com/git-ai-project/git-ai/tree/main/skills/prompt-analysis

These skills are installed into the ~/.git-ai/skills directory by

git-ai/src/mdm/skills_installer.rs

Line 126 in ad241de

pub fn install_skills(dry_run: bool, _verbose: bool) -> Result<SkillsInstallResult, GitAiError> {

[ ] Ensure compatibility Agent's Skill "marketplaces"
[ ] Document install instructions per-agent (let's avoid auto-installing the skills)