fix: auto-elevate to root via sudo or doas in install script

- Script now re-executes itself with 'sudo' if available (or 'doas' as fallback)
- No need to prefix with sudo/doas — just run ./install-gitea-runner.sh ...
- Falls back to clear error if neither sudo nor doas is installed

scripts/install-gitea-runner.sh

@@ -26,15 +26,18 @@ if [ -z "$TOKEN" ] || [ -z "$NAME" ] || [ -z "$LABELS" ]; then
     exit 1
 fi
 
-# ── 0. Require root ────────────────────────────────────────────────
+# ── 0. Require root — auto-elevate if possible ────────────────────
 if [ "$(id -u)" -ne 0 ]; then
-    echo "❌ This script must be run as root."
-    if [ -f /etc/alpine-release ]; then
-        echo "   Use: doas $0 $*"
+    # Try to re-execute with available privilege escalation
+    if command -v sudo >/dev/null 2>&1; then
+        exec sudo "$0" "$@"
+    elif command -v doas >/dev/null 2>&1; then
+        exec doas "$0" "$@"
     else
-        echo "   Use: sudo $0 $*"
+        echo "❌ This script must be run as root."
+        echo "   Install sudo or doas, or run as root directly."
+        exit 1
     fi
-    exit 1
 fi
 
 # ── 0. Detect OS + privilege elevation method ──────────────────────