feat(sshd-setup): multi-distro support and verification steps

- sshd-setup.sh: Auto-detect OS (Debian/Ubuntu/Fedora/RHEL/CentOS)
- Use appropriate package manager (apt-get vs dnf)
- Add verification steps after each major phase
- Exit with error if sshd installation fails
- Exit with error if sshd doesn't start successfully
- Add troubleshooting section in output

- kugetsu-install.sh: Add verification that kugetsu binary exists

- kugetsu-setup.md: Document multi-distro installation commands

skills/kugetsu/scripts/sshd-setup.sh

@@ -7,12 +7,44 @@ echo "=== kugetsu SSH Setup ==="
 echo "Target user: $USERNAME"
 echo ""
 
+detect_os() {
+    if [ -f /etc/os-release ]; then
+        . /etc/os-release
+        case "$ID" in
+            debian|ubuntu|"noble"|"jammy"|"focal"|"bionic"|"bullseye"|"bookworm"|"trixie"|"sid")
+                echo "debian"
+                ;;
+            fedora|rhel|centos|rocky|alma)
+                echo "fedora"
+                ;;
+            *)
+                echo "unknown"
+                ;;
+        esac
+    else
+        echo "unknown"
+    fi
+}
+
+OS_TYPE=$(detect_os)
+echo "Detected OS: $OS_TYPE"
+
 if ! command -v systemctl &> /dev/null; then
     echo "ERROR: systemd not found."
     echo ""
     echo "This script requires systemd to be installed and running inside the container."
     echo "Please install systemd first:"
-    echo "    apt-get update && apt-get install -y systemd"
+    case "$OS_TYPE" in
+        debian)
+            echo "    apt-get update && apt-get install -y systemd"
+            ;;
+        fedora)
+            echo "    dnf install -y systemd"
+            ;;
+        *)
+            echo "    Install systemd using your package manager"
+            ;;
+    esac
     echo ""
     echo "If you are running in a container that doesn't support systemd, consider:"
     echo "    - Using a container image with systemd support"
@@ -20,13 +52,36 @@ if ! command -v systemctl &> /dev/null; then
     exit 1
 fi
 
-echo "[1/6] Updating package lists..."
-apt-get update -qq
+echo ""
+echo "=== Step 1: Install openssh-server ==="
+case "$OS_TYPE" in
+    debian)
+        echo "Using apt-get (Debian/Ubuntu)..."
+        apt-get update -qq
+        apt-get install -y -qq openssh-server sudo
+        ;;
+    fedora)
+        echo "Using dnf (Fedora/RHEL)..."
+        dnf install -y -q openssh-server sudo
+        ;;
+    *)
+        echo "ERROR: Unsupported OS. Please install openssh-server and sudo manually."
+        exit 1
+        ;;
+esac
 
-echo "[2/6] Installing openssh-server..."
-apt-get install -y -qq openssh-server sudo
+echo ""
+echo "=== Step 2: Verify installation ==="
+if ! command -v sshd &> /dev/null; then
+    echo "ERROR: sshd installation failed."
+    echo "Please verify openssh-server was installed correctly."
+    exit 1
+fi
+echo "sshd binary: $(which sshd)"
+echo "sshd version: $(sshd -V 2>&1 | head -1)"
 
-echo "[3/6] Creating user '$USERNAME' if not exists..."
+echo ""
+echo "=== Step 3: Create user '$USERNAME' ==="
 if ! id "$USERNAME" &> /dev/null; then
     useradd -m -s /bin/bash "$USERNAME"
     echo "User '$USERNAME' created."
@@ -34,27 +89,40 @@ else
     echo "User '$USERNAME' already exists."
 fi
 
-echo "[4/6] Configuring SSH for key-only authentication..."
+echo ""
+echo "=== Step 4: Configure SSH for key-only authentication ==="
 SSHD_CONFIG="/etc/ssh/sshd_config"
 sed -i 's/^#*PasswordAuthentication.*/PasswordAuthentication no/' "$SSHD_CONFIG"
 sed -i 's/^#*PubkeyAuthentication.*/PubkeyAuthentication yes/' "$SSHD_CONFIG"
 sed -i 's/^#*PermitRootLogin.*/PermitRootLogin no/' "$SSHD_CONFIG"
 echo "SSH configured: key-only auth, root login disabled."
 
-echo "[5/6] Configuring sudo for passwordless access..."
+echo ""
+echo "=== Step 5: Configure sudo for passwordless access ==="
 SUDOERS_FILE="/etc/sudoers.d/$USERNAME"
 echo "$USERNAME ALL=(ALL) NOPASSWD: ALL" > "$SUDOERS_FILE"
 chmod 0440 "$SUDOERS_FILE"
 echo "Sudo configured: $USERNAME can run sudo without password."
 
-echo "[6/6] Enabling and starting sshd..."
+echo ""
+echo "=== Step 6: Enable and start sshd ==="
 systemctl enable sshd
 systemctl restart sshd
 
+sleep 1
+
+echo ""
+echo "=== Step 7: Verify sshd is running ==="
 if systemctl is-active --quiet sshd; then
-    echo "sshd is running."
+    echo "SUCCESS: sshd is running."
+    echo "Status:"
+    systemctl status sshd --no-pager | head -5
 else
-    echo "WARNING: sshd may not have started correctly. Check with: systemctl status sshd"
+    echo "ERROR: sshd is not running."
+    echo "Debug info:"
+    systemctl status sshd --no-pager
+    journalctl -u sshd -n 10 --no-pager
+    exit 1
 fi
 
 echo ""
@@ -72,8 +140,14 @@ echo ""
 echo "2. Connect from remote:"
 echo "   ssh -p 2222 $USERNAME@<container-host-ip>"
 echo ""
-echo "   (Requires host-side port forwarding - see docs/kugetsu-setup.md)"
-echo ""
 echo "3. Verify SSH access:"
 echo "   ssh -p 2222 $USERNAME@<container-host-ip> sudo systemctl status sshd"
+echo ""
+echo "=== Troubleshooting ==="
+echo ""
+echo "If SSH connection fails:"
+echo "  - Check sshd is running: systemctl status sshd"
+echo "  - Check sshd logs: journalctl -u sshd -n 20"
+echo "  - Verify user exists: id $USERNAME"
+echo "  - Verify SSH key was added: cat /home/$USERNAME/.ssh/authorized_keys"
 echo ""