Refactor aios: Focus on Claude Code + aigpt simplicity

Simplified aios to focus on core value:
- Pre-configured systemd-nspawn environment
- Claude Code + aigpt (MCP) pre-installed
- Shared memory across containers

Philosophy:
Don't build new tools. Use existing ones (Claude Code, systemd-nspawn).
Just provide the optimal environment and automation.

Changes:
- Added cfg/zshrc: Shell config with claude alias
- Updated build.zsh: Install Claude Code (npm) + aigpt
- Updated aios-install.sh: Simplified installation flow
- Updated README.md: Focus on simplicity and practicality

Installation:
1. npm i -g @anthropic-ai/claude-code
2. Build aigpt from source
3. Configure .zshrc with aliases
4. Set up systemd-nspawn with bind mounts

Usage:
$ sudo machinectl shell aios
$ claude  # or: ai

cfg/zshrc

@@ -0,0 +1,40 @@
+# aios .zshrc
+# AI-managed OS with Claude Code + aigpt
+
+# Environment
+export EDITOR=vim
+export LANG=en_US.UTF-8
+
+# Path
+export PATH=$HOME/.local/bin:$PATH
+
+# aigpt MCP configuration
+export AIGPT_CONFIG="$HOME/.config/syui/ai/config.toml"
+export AIGPT_MCP="$HOME/.config/syui/ai/mcp.json"
+
+# Aliases
+alias ai='claude'
+alias c='claude'
+
+# Prompt
+autoload -Uz promptinit
+promptinit
+prompt adam1
+
+# History
+HISTFILE=~/.zsh_history
+HISTSIZE=10000
+SAVEHIST=10000
+setopt SHARE_HISTORY
+
+# Completion
+autoload -Uz compinit
+compinit
+
+# Welcome message
+echo "aios - AI-managed OS"
+echo "  aigpt: MCP server for shared memory"
+echo "  claude: AI conversation interface"
+echo ""
+echo "Type 'claude' or 'ai' to start"
+echo ""