✨ feat(region): seed offline chinese input

- ✨ make first-login pinyin available without downloads
- ⌨️ preserve compose and terminal prefix shortcuts

Amp-Thread-ID: https://ampcode.com/threads/T-01a0df38-0ea7-759b-bcff-29da223cc567
Co-authored-by: Amp <amp@ampcode.com>

default/regions/cn/packages

@@ -0,0 +1,5 @@
+# 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

default/regions/cn/pacman/mirrorlist.append

@@ -0,0 +1 @@
+Server = https://mirrors.ustc.edu.cn/archlinux/$repo/os/$arch

default/regions/cn/pacman/pacman.conf.append

@@ -0,0 +1,2 @@
+[archlinuxcn]
+Server = https://mirrors.ustc.edu.cn/archlinuxcn/$arch

default/regions/cn/skel/.config/fcitx5/config

@@ -0,0 +1,14 @@
+[Hotkey]
+EnumerateWithTriggerKeys=False
+# Keep lone Shift and Ctrl+Shift available to applications and CapsLock.
+AltTriggerKeys=
+EnumerateForwardKeys=
+EnumerateBackwardKeys=
+
+[Hotkey/TriggerKeys]
+# Ctrl+Space belongs to tmux/Herdr; CapsLock remains the Compose key.
+0=Alt+space
+
+[Behavior]
+# Start in direct input; Alt+Space activates offline Simplified Chinese Pinyin.
+ActiveByDefault=False

default/regions/cn/skel/.config/fcitx5/profile

@@ -0,0 +1,12 @@
+[Groups/0]
+Name=Default
+# Fcitx requires a nonempty group layout. Leave item layouts unset so it uses
+# the compositor's keymap; the base xcb.conf also disables XKB overrides.
+Default Layout=us
+DefaultIM=pinyin
+
+[Groups/0/Items/0]
+Name=keyboard-us
+
+[Groups/0/Items/1]
+Name=pinyin