@ autocomplete should include untracked files in the project directory

Feature Request

The @ file autocomplete in Claude Code only shows git-tracked files. This makes it impossible to autocomplete files that are intentionally untracked (e.g., files listed in .git/info/exclude).

Use Case

In team projects, developers often have personal configuration or planning files under .claude/ (e.g., settings.local.json, docs/plans/) that should not be committed to the repository. The natural approach is to keep them untracked via .git/info/exclude.

However, this means @ autocomplete no longer finds these files, forcing users to type full paths manually every time.

Current Workaround

• Type file paths manually (inconvenient)
• Commit the files and use git update-index --skip-worktree (hacky, pollutes the repo with personal files)

Proposed Solution

Include untracked files (at least those within the project directory) in @ autocomplete results, or provide a configuration option to do so.

A possible approach: use filesystem listing in addition to git ls-files, perhaps limited to specific directories like .claude/.