🔥 refactor(region): drop input defaults from the cn profile

- 🔥 keep this change to the regional build architecture; Chinese input gets its own proposal instead of fixing one engine here
- ✅ assert the shipped profile adds only its repository keyring

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K3Jna1ogUUviYLJzhsG6Vr

default/regions/cn/packages

@@ -1,5 +1,2 @@
 # Installed from the ISO's offline repository before enabling ArchLinuxCN.
 archlinuxcn-keyring
-# Reuse the base Fcitx5 service and toolkit integration. libime supplies the
-# offline Pinyin dictionary/model through this package's dependencies.
-fcitx5-chinese-addons