v0.3.4

Small readability polish on the sync output.

What's new

Visible separator between shipped and user guidelines

When package-boost:sync writes the <package-boost-guidelines>
block and both sources contribute content, a --- horizontal rule is
now emitted between the shipped foundation and the user's
.ai/guidelines/ content. Readers skimming CLAUDE.md / AGENTS.md
can tell at a glance where the shipped defaults end and project-
specific overrides begin.

Example:

<package-boost-guidelines>
# Package Boost Guidelines

## Foundational Context
...

## Replies

Be concise. Focus on what changed and why.

---

# Release Automation
...
</package-boost-guidelines>

No divider is emitted when only one of the two sources is present, so
a repo with just the shipped foundation (or just user guidelines)
still renders clean.

Full Changelog: 0.3.3...0.3.4