Add native config option to include gitignored files in search

[xiaocang]

Summary

Previous issues #1535 and #2517 requested the ability to include gitignored files in search results. They were closed with workarounds (RIPGREP_CONFIG_PATH, .ignore files).

This proposes a native respect_gitignore config option for a cleaner UX.

Proposed Solution

Add a respect_gitignore boolean config option:

{
  "respect_gitignore": false
}

• Default: true (current behavior, respects .gitignore)
• When false: includes gitignored files in glob/grep/ls results

Benefits over workarounds

• No extra files (.ignore, .rgrc) needed
• No environment variables required
• Discoverable in config schema
• Consistent across all search tools (glob, grep, ls)

Use Cases

• Debugging build outputs or generated code
• Referencing LLM-specific docs/plans not committed to repo
• Working with vendored dependencies
• Inspecting files in directories like node_modules