install.sh: skip pip when requests is already system-wide

PEP 668 Debian 13 systems error out on 'pip install --user'. Runtime
only needs requests; pytest+requests-mock are test-only. Detect the
runtime dep first and fall back to pip only when missing.

install.sh

@@ -19,15 +19,20 @@ if mountpoint -q "$HOME/pCloudDrive" 2>/dev/null; then
   mkdir -p "$PCLOUD_TARGET"
 fi
 
-# Install dependencies
-echo "Installing dependencies..."
-if ! pip install --user requests requests-mock pytest 2>&1 | tail -5; then
+# Install runtime dependency (requests) if missing. Dev deps (pytest, requests-mock)
+# are only needed by the test suite — install them separately in a venv if you plan to test.
+if python3 -c "import requests" 2>/dev/null; then
+  echo "Runtime dep 'requests' already importable system-wide; skipping pip install."
+else
+  echo "Installing runtime dependency: requests"
+  if ! pip install --user requests 2>&1 | tail -5; then
     echo "ERROR: pip install --user failed (PEP 668 externally-managed environment?)."
-  echo "To install in a virtualenv instead, run:"
-  echo "  python3 -m venv ~/tools/coe-mirror/.venv"
-  echo "  source ~/tools/coe-mirror/.venv/bin/activate"
-  echo "  pip install requests requests-mock pytest"
+    echo "To install in a virtualenv instead:"
+    echo "  python3 -m venv $TOOL_DIR/.venv"
+    echo "  $TOOL_DIR/.venv/bin/pip install requests"
+    echo "  # then edit systemd/coe-mirror.service ExecStart to point at the venv python"
     exit 1
+  fi
 fi
 
 # Copy unit files