fix: check-deps installs all required system packages via apt

scripts/check_deps.sh now checks and installs all prerequisites:
git, curl, openssl, python3, python3-cryptography, docker, docker-compose.
Runs apt-get update only once if anything needs installing.
Also adds current user to docker group if missing.
Makefile calls it with sudo so it has the rights to install packages.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Makefile

@@ -39,7 +39,7 @@ help:
 
 # Setup commands
 check-deps:
-	@sh scripts/check_deps.sh
+	@sudo sh scripts/check_deps.sh
 
 setup: check-deps
 	@echo "Setting up Personal Internet Cell..."

scripts/check_deps.sh

@@ -1,48 +1,56 @@
 #!/bin/sh
-# Install Python dependencies needed by setup_cell.py
+# Install all host dependencies required by Personal Internet Cell.
+# Uses apt-get (Debian/Ubuntu). Must be run with sudo or as root.
 set -e
 
-echo "Checking system dependencies..."
+APT_UPDATED=0
 
-# Ensure python3 is available
-if ! command -v python3 >/dev/null 2>&1; then
-    echo "Installing python3..."
-    sudo apt-get install -y python3 || { echo "ERROR: python3 not found and could not install it."; exit 1; }
+apt_install() {
+    PKG="$1"
+    if ! dpkg -s "$PKG" >/dev/null 2>&1; then
+        echo "  Installing $PKG..."
+        if [ "$APT_UPDATED" = "0" ]; then
+            apt-get update -qq
+            APT_UPDATED=1
+        fi
+        apt-get install -y -qq "$PKG"
+    else
+        echo "  [ok] $PKG"
+    fi
+}
+
+echo "=== Checking system dependencies ==="
+
+# Core tools
+apt_install git
+apt_install curl
+apt_install openssl
+apt_install python3
+apt_install python3-cryptography
+
+# Docker
+if ! command -v docker >/dev/null 2>&1; then
+    echo "  Installing docker..."
+    if [ "$APT_UPDATED" = "0" ]; then
+        apt-get update -qq
+        APT_UPDATED=1
+    fi
+    apt-get install -y -qq docker.io
+fi
+echo "  [ok] docker"
+
+# Docker Compose (v2 plugin preferred, v1 fallback)
+if ! docker compose version >/dev/null 2>&1 && ! command -v docker-compose >/dev/null 2>&1; then
+    echo "  Installing docker-compose..."
+    apt-get install -y -qq docker-compose
+fi
+echo "  [ok] docker-compose"
+
+# Ensure current user is in docker group
+if ! id | grep -q '(docker)'; then
+    echo "  Adding $(id -un) to docker group..."
+    usermod -aG docker "$(id -un)"
+    echo "  NOTE: Log out and back in (or run 'newgrp docker') for docker group to take effect."
 fi
 
-# Check if cryptography is already importable
-if python3 -c "import cryptography" 2>/dev/null; then
-    echo "Dependencies OK."
-    exit 0
-fi
-
-echo "Installing python3-cryptography..."
-
-# 1. Try apt (works if sudo is passwordless or interactive TTY is available)
-if sudo -n apt-get install -y python3-cryptography 2>/dev/null; then
-    echo "Dependencies OK."
-    exit 0
-fi
-
-# 2. Try pip (module form, covers both pip3 and python3 -m pip)
-if python3 -m pip install --user cryptography 2>/dev/null; then
-    echo "Dependencies OK."
-    exit 0
-fi
-
-# 3. Bootstrap pip via get-pip.py, then install
-if command -v curl >/dev/null 2>&1; then
-    curl -sSL https://bootstrap.pypa.io/get-pip.py -o /tmp/get-pip.py 2>/dev/null \
-        && python3 /tmp/get-pip.py --user -q 2>/dev/null \
-        && python3 -m pip install --user cryptography 2>/dev/null \
-        && { echo "Dependencies OK."; exit 0; }
-fi
-
-# 4. No automated path worked — ask the user to install manually
-echo ""
-echo "ERROR: Could not install python3-cryptography automatically."
-echo "Please run the following command and then retry:"
-echo ""
-echo "  sudo apt-get install -y python3-cryptography"
-echo ""
-exit 1
+echo "=== All dependencies OK ==="