feat(deployment): replace monster scripts with modular helper scripts (#87)

- Add install.sh orchestrator with upgrade support
- Add 6 helper scripts (<100 lines each) replacing 700-800 line monsters
- Add deployment/linux/furt.service systemd template
- Support both fresh install and upgrade modes
- Platform-aware detection (OpenBSD/FreeBSD vs Linux)
- Skip user/service creation in upgrade mode
- Preserve existing configuration during updates
- Remove merkwerk dependency from production install script

Helper scripts:
- scripts/setup-user.sh - Create system user (_furt/furt)
- scripts/setup-directories.sh - Create directory structure
- scripts/sync-files.sh - Copy source files to installation
- scripts/create-service.sh - Create system service from templates
- scripts/validate-config.sh - Validate furt.conf syntax
- scripts/health-check.sh - Basic health check functionality

Closes DAW/furt#87

scripts/health-check.sh

@@ -0,0 +1,40 @@
+#!/bin/sh
+# scripts/health-check.sh - Basic health check for furt service
+
+set -e
+
+# Default values
+HOST="127.0.0.1"
+PORT="7811"
+
+# Parse command line arguments
+while [ $# -gt 0 ]; do
+    case "$1" in
+        --host) HOST="$2"; shift 2 ;;
+        --port) PORT="$2"; shift 2 ;;
+        *) echo "Usage: $0 [--host HOST] [--port PORT]"; exit 1 ;;
+    esac
+done
+
+echo "Checking furt health at $HOST:$PORT..."
+
+# Check if port is listening
+if command -v curl >/dev/null 2>&1; then
+    if curl -s "http://$HOST:$PORT/health" > /tmp/health_response; then
+        echo "Health check successful:"
+        cat /tmp/health_response | sed 's/^/  /'
+        rm -f /tmp/health_response
+    else
+        echo "Health check failed - service not responding"
+        exit 1
+    fi
+else
+    echo "Warning: curl not available, using basic port check"
+    if nc -z "$HOST" "$PORT" 2>/dev/null; then
+        echo "Port $PORT is listening on $HOST"
+    else
+        echo "Port $PORT is not accessible on $HOST"
+        exit 1
+    fi
+fi
+