feat: Add optional auto-startup for claude

- Create cfg/aios.zsh startup script with config-based claude launch
- Install startup script to /usr/local/bin/aios-startup
- Create default config at ~/.config/syui/ai/os/config.json
- Source startup script from user 'ai' .zshrc
- Enable optional "shell mode" via config {"shell": true}

cfg/aios.zsh

@@ -0,0 +1,28 @@
+#!/bin/zsh
+# aios startup script
+
+CONFIG_DIR="$HOME/.config/syui/ai/os"
+CONFIG_FILE="$CONFIG_DIR/config.json"
+
+# 設定ファイルが存在しない場合は何もしない
+if [ ! -f "$CONFIG_FILE" ]; then
+    return
+fi
+
+# jqで設定読み込み
+if ! command -v jq &>/dev/null; then
+    return
+fi
+
+SHELL_MODE=$(cat "$CONFIG_FILE" | jq -r '.shell // false')
+
+if [ "$SHELL_MODE" = "true" ]; then
+    echo "aios - AI-managed OS"
+    echo "  Shell mode enabled"
+    echo ""
+
+    # claudeを起動
+    if command -v claude &>/dev/null; then
+        exec claude
+    fi
+fi