build: Packages/ directory with 91 pkgar files + auto-sync script

Packages/ is the canonical binary package repository for Red Bear OS.
Contains stage.pkgar copies of all built packages (91 files).

New scripts:
- local/scripts/sync-packages.sh: syncs built pkgar → Packages/
- make packages-sync: run sync
- make packages-list: list package count

Future: cache-auto will auto-sync to Packages/ after each build.

.gitignore

@@ -81,3 +81,4 @@ local/cache/pkgar/
 # Red Bear git-tracked build cache (survives make clean)
 !local/cache/pkgar/
 !local/cache/pkgar/**
+Packages/redbear-firmware.pkgar