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

cn/registry/ai-harnesses.json

@@ -1,5 +1,5 @@
 {
-  "_verified": "2026-08-24",
+  "_verified": "2026-08-25",
   "harnesses": {
     "claude-code": {
       "display_name": "Claude Code",
@@ -25,7 +25,7 @@
     "kimi-code": {
       "display_name": "Kimi Code CLI",
       "command": "kimi",
-      "install": "doc:https://www.kimi.com/code/docs/en/",
+      "install": "omarchy-cn-kimi-install",
       "config_method": "native",
       "protocol": "native"
     },