Implement aios initial direction: AI-managed OS with shared memory

This commit implements the new direction for aios:
- AI conversation interface replaces traditional shell
- aigpt integration for shared memory across containers
- systemd-nspawn for environment isolation

Changes:
- Added aios-install.sh: Complete installer script
- Added cfg/mcp.json: MCP server configuration for aigpt
- Added cfg/config.toml: aios configuration with permission system
- Added cfg/nspawn/aios.nspawn: systemd-nspawn configuration
- Updated build.zsh: Integrated aigpt installation and setup
- Updated README.md: Documented new architecture and philosophy

Architecture:
User → AI Chat → Commands → Execution
         ↓
     aigpt (shared memory)
         ↓
  systemd-nspawn (isolated environment)

Philosophy:
Simply insert AI into existing flows (shell → AI chat)

cfg/nspawn/aios.nspawn

@@ -0,0 +1,16 @@
+# systemd-nspawn configuration for aios
+# Place this file in /etc/systemd/nspawn/aios.nspawn
+
+[Exec]
+Boot=yes
+PrivateUsers=pick
+ResolvConf=copy-host
+
+[Files]
+# Bind mount shared memory directory
+# Host: ~/.config/syui/ai -> Container: /root/.config/syui/ai
+Bind=%h/.config/syui/ai:/root/.config/syui/ai
+
+[Network]
+Private=yes
+VirtualEthernet=yes