Add mddocs status command and --version flag

[devYRPauli]

Two human-side CLI quality-of-life additions.

mddocs status

A repo-wide inbox: lists every open comment and pending suggestion across all managed docs in one command, grouped by file with a summary footer. No more running comment ls / suggest ls per file to find what needs attention.

• Default view shows only actionable items (open comments + pending suggestions); docs with nothing open are omitted.
• --all also lists resolved comments and accepted/rejected suggestions.
• Friendly "Nothing open. All caught up." when there is nothing to show.

Reuses the existing listManagedDocs + loadDoc primitives and mirrors the existing ls line formats, so there are no changes to the engine package.

mddocs --version / -v

Reports the installed version (previously errored with unknown option). The value comes from the published package's own package.json via the launcher, falling back to 0.0.0-dev in a dev checkout.

Tests

• status: grouping, omission of docs with nothing open, footer counts, --all inclusion, and the empty-repo message.
• --version: reports the resolved version and the dev fallback.
• Updated the command-list assertion to include status.

Full CLI suite and typecheck pass.