feat(ui): append space automatically after file completion

[Grin1024]

Description:

This PR improves the shell autocomplete experience for file mentions.

Changes:

• UX Improvement : When a user selects a file from the @ mention list (e.g., README.md ), the completer now automatically appends a space (resulting in README.md ). This allows users to immediately continue typing their query without manually adding a separator.
• Logic : The logic checks if the candidate text ends with / . If not (implying it is a file), a space is appended.
• Tests : Updated test_top_level_paths_skip_ignored_names to match the new behavior.

Related Issue

Resolve

Description

Checklist

• I have read the CONTRIBUTING document.
• I have linked the related issue, if any.
• I have added tests that prove my fix is effective or that my feature works.
• I have run make gen-changelog to update the changelog.
• I have run make gen-docs to update the user documentation.

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

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