Respect .rooignore in @ dropdown / context mention selector

[chunjuaner05]

Motivation

When using the "@" file/folder picker in Roo Code, ignored folders according to .rooignore are still shown. This clutters the UI and can expose sensitive paths.

Suggestion

Make the @ picker respect .rooignore rules, hiding or marking ignored directories (like archive/) in the dropdown.

Benefits

• Cleaner, less noisy file selection UI
• Better privacy and consistency between Roo tools and UI
• Aligns with existing .rooignore behavior in other parts of the extension

Examples / References

• .rooignore works for file access and mentions :contentReference[oaicite:9]{index=9}
• Related discussion: Exclude list of files & folders from the context to avoid noise #1918 :contentReference[oaicite:10]{index=10}