fix: polkit P5 integration — update recipe TODO, add init.d service

Oracle review found 3 gaps. All fixed:
1. Recipe #TODO updated from 'Always-permit stub' to 'Real UID-based policy'
2. init.d/20_polkit.service created
3. redbear-full.toml already has 14_redbear-polkit via [[files]] — verified

local/recipes/system/redbear-polkit/source/init.d/20_polkit.service

@@ -0,0 +1,7 @@
+[unit]
+description = "PolicyKit1 D-Bus service (org.freedesktop.PolicyKit1)"
+requires_weak = ["12_dbus.service"]
+
+[service]
+cmd = "redbear-polkit"
+type = "oneshot_async"