build: suppress non-essential packages, fix dbus epoll, add git cache

- Suppress curl and git (non-essential for boot, build issues)
- D-Bus: disable epoll (-Depoll=disabled) for relibc compat
- Cookbook: revert skip-on-missing (broke sysroot install)
- Cache system: git-tracked pkgar in local/cache/pkgar/
- Rebuild progress: redox-driver-sys, iommu, kernel, kf6-ecm, dbus done

config/redbear-full.toml

@@ -102,6 +102,8 @@ cosmic-edit = "ignore"
 cosmic-files = "ignore"
 cosmic-icons = "ignore"
 cosmic-term = "ignore"
+curl = "ignore"
+git = "ignore"
 
 [[files]]
 path = "/lib/firmware/amdgpu"