FOLLOW-UP: Share slugifyHeading between auto_tasks.go and markdown.go (from PR #145)

[adnaan]

Context

This follow-up task was identified during the review of PR #145.

Source PR: #145
PR Title: feat: auto-interactive markdown checkboxes
Suggested by: @claude-bot
Priority: Low

Task Description

Currently there are two independent slug functions:

• slugifyHeading() in auto_tasks.go (root package)
• slugify() in internal/source/markdown.go

Both convert heading text to URL-safe anchors (GitHub-style), and they must produce identical output for anchor matching to work. Currently this is documented with a comment warning, but there's no enforcement.

Options:

1. Extract to a shared internal package (e.g., internal/slug)
2. Add a test that compares both implementations against a test matrix
3. Have one call the other via import

Original Comment

The comment warns about keeping this in sync, but there's no enforcement. Consider extracting to a shared package, adding a test that compares both implementations, or using the same function via import.

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This issue was automatically created by prmonitor from PR review comments.