feat: Add ignore-conda-prefix flag to pixi-global

[hoxbro]

Description

For some of the pixi global executable I don't want to have the CONDA_PREFIX enabled as this can interfere with the tool. So for the longest time I have left the exposed section empty and made a symlink to a dir on my path ln -sf "$PIXI_HOME/envs/nvim/bin/nvim" ~/.local/bin/nvim

Not sure if this feature should be exposed in the CLI.

How Has This Been Tested?

Tested functionality locally with cargo run --bin pixi global install uv --ignore-conda-prefix and looked at the trampoline configuration file.

Will also take a look at how the CI react to my changes 😅

AI Disclosure

• This PR contains AI-generated content.
  • I have tested any AI-generated content in my PR.
  • I take responsibility for any AI-generated content in my PR.

Tools: Claude Code: Sonnet 4.6

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added sufficient tests to cover my changes.
• I have verified that changes that would impact the JSON schema have been made in schema/model.py.