Fix China app installs and wire the CN AI stack into Install > AI

Offline installs ship no pacman sync db, so yay resolved official
repo dependencies as AUR packages and every catalog install failed;
omarchy-cn-app-install now runs a full -Syu first (verified end to
end: WeChat builds and installs in the VM). Kimi Code gains a real
installer command reused by the harness registry, the default-agent
path, and new Install > AI entries (Kimi Code, Deep Code, AI Hub),
and the AI Hub wizard offers to launch native harnesses immediately
so their official CLI login runs, matching how Claude Code works.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QKxGW1raAWaqeU8WdHsMsp

bin/omarchy-default-agent

@@ -50,13 +50,10 @@ if [[ $agent == "kimi" ]]; then
     if [[ $installing == "false" ]]; then
       exec omarchy-launch-floating-terminal-with-presentation omarchy-default-agent --install kimi
     fi
-    installer=$(mktemp)
-    if ! curl -fsSL https://code.kimi.com/kimi-code/install.sh -o "$installer" || ! bash "$installer"; then
-      rm -f "$installer"
+    if ! omarchy-cn-kimi-install; then
       echo "Could not install $name with the official installer" >&2
       exit 1
     fi
-    rm -f "$installer"
   fi
 else
   if [[ $installing == "false" ]] && ! mise where "$agent_package" &>/dev/null; then