fix(scan): preserve whitespace in Git paths - #868

Description

ocr scan already asks git ls-files for NUL-delimited paths, but then
applies strings.TrimSpace to every returned filename. Valid tracked files
whose names begin or end with whitespace are therefore changed before the
scanner opens them.

For example, Git returns these exact paths:

< leading.go>
<trailing.go >

The scanner previously attempted to stat leading.go and trailing.go
instead. Both lookups failed and the files silently disappeared from the scan.

This change keeps each NUL-delimited Git path exact while continuing to ignore
genuinely empty records. User-supplied ocr scan path filters retain their
existing whitespace normalization.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Refactoring (no functional changes)
• Documentation update
• CI / Build / Tooling

How Has This Been Tested?

• make check
• make test
• make build
• make coverage - 90.2%, meeting the 90% threshold
• Real temporary Git repository with leading- and trailing-space paths

Before the fix, the regression test logged two cannot stat warnings and
returned no scan items. After the fix, both files are enumerated under their
exact names. The focused test and full suite pass with the race detector.

The trailing-space fixture is skipped on Windows because the filesystem cannot
represent that filename; Windows cross-compilation remains covered by CI.

Self-review used OCR Delegation Mode with the host agent:
2/2 changed files reviewed, 0 skipped, 0 findings.

Checklist

• My code follows the project's coding style (go fmt, go vet)
• I have performed a self-review of my code
• I have added tests that prove my fix is effective or my feature works
• New and existing unit tests pass locally with my changes
• Documentation is not required for this internal enumeration fix
• I have signed the CLA

Related Issues

No existing issue found. All open issues, pull request text, and open pull
request changed files were checked before implementation; no competing scan
path-enumeration change was found.