fix: Restructure containers - aios contains child containers internally

Changed from 3 separate containers to 1 container with child containers inside:
- /var/lib/machines/aios/ (main container)
  - /var/lib/machines/restore-img/ (child container)
  - /var/lib/machines/workspace/ (child container)

ai user operates child containers from within aios using machinectl.

cfg/aios-ctl.zsh

@@ -21,9 +21,9 @@ function aios-shell() {
     sudo machinectl shell $NAME
 }
 
-# Login to aios container
+# Login to aios container as ai user
 function aios-login() {
-    sudo machinectl login $NAME
+    sudo machinectl shell $NAME /bin/su - ai
 }
 
 # Create backup of current aios

cfg/install.sh

@@ -27,19 +27,17 @@ fi
 echo "1. Extracting $TARBALL..."
 tar xf "$TARBALL"
 
-# Move all containers to /var/lib/machines/
-echo "2. Installing containers to /var/lib/machines/..."
-rm -rf /var/lib/machines/$NAME /var/lib/machines/$BACKUP /var/lib/machines/workspace
+# Install aios (contains child containers inside)
+echo "2. Installing aios to /var/lib/machines/..."
+rm -rf /var/lib/machines/$NAME
 mkdir -p /var/lib/machines
 mv root.x86_64/var/lib/machines/arch /var/lib/machines/$NAME
-mv root.x86_64/var/lib/machines/aiosback /var/lib/machines/$BACKUP
-mv root.x86_64/var/lib/machines/workspace /var/lib/machines/workspace
 
 # Copy nspawn configuration
 echo "3. Installing systemd-nspawn configuration..."
 mkdir -p /etc/systemd/nspawn
 
-# Create aios.nspawn
+# Create aios.nspawn (only one container needed)
 cat > /etc/systemd/nspawn/$NAME.nspawn <<'EOF'
 [Exec]
 Boot=yes
@@ -53,34 +51,6 @@ Bind=/root/.config/syui/ai:/root/.config/syui/ai
 VirtualEthernet=no
 EOF
 
-# Create aiosback.nspawn
-cat > /etc/systemd/nspawn/$BACKUP.nspawn <<'EOF'
-[Exec]
-Boot=yes
-PrivateUsers=pick
-ResolvConf=copy-host
-
-[Files]
-Bind=/root/.config/syui/ai:/root/.config/syui/ai
-
-[Network]
-VirtualEthernet=no
-EOF
-
-# Create workspace.nspawn
-cat > /etc/systemd/nspawn/workspace.nspawn <<'EOF'
-[Exec]
-Boot=yes
-PrivateUsers=pick
-ResolvConf=copy-host
-
-[Files]
-Bind=/root/.config/syui/ai:/root/.config/syui/ai
-
-[Network]
-VirtualEthernet=no
-EOF
-
 # Create bind mount directory
 mkdir -p /root/.config/syui/ai