Add pinned launcher-catalog daily-care runtime

[lukisch]

Summary

• port the canonical launcher-catalog reconciler into the Plan-D SoftwareCenter repository
• require exact catalog, desktop registry, software-root, and local-dev-root CLI inputs; keep dry-run as the default
• preserve both QSettings profiles, SUPPRESSED semantics, no-shell execution, local backups, automatic compensation, and an explicit restore path
• document a pinned-runtime scheduler candidate, native readbacks, and rollback without changing the live scheduler or Windows Task

Verification

• python -m pytest -q tests/test_softwarecenter_sync.py -> 35 passed
• python -m pytest -q -> 161 passed
• ruff check scripts/softwarecenter_sync.py tests/test_softwarecenter_sync.py -> passed
• real read-only run against the 59-entry canonical catalog -> exit 0; catalog and DESKTOP-REGISTRY SHA-256 unchanged
• independent read-only review -> no open P1/P2

Safety boundary

This PR changes source and documentation only. It does not modify OneDrive source files, QSettings profiles, the live ellmos-scheduler database, or the Windows Scheduled Task.