Fix kimi install error masking, prompt flag, and setup default hop

The official installer downloads to a temp file so curl failures
cannot be masked by the pipe; Kimi prompts use --prompt per the CLI
reference; the AI Hub wizard now offers omarchy-cn-ai-default for
claude-code/codex profiles so the combo really becomes the default
agent.

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

bin/omarchy-default-agent

@@ -50,10 +50,13 @@ if [[ $agent == "kimi" ]]; then
     if [[ $installing == "false" ]]; then
       exec omarchy-launch-floating-terminal-with-presentation omarchy-default-agent --install kimi
     fi
-    if ! curl -fsSL https://code.kimi.com/kimi-code/install.sh | bash; then
+    installer=$(mktemp)
+    if ! curl -fsSL https://code.kimi.com/kimi-code/install.sh -o "$installer" || ! bash "$installer"; then
+      rm -f "$installer"
       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