feat: Complete MEDIUM priority security features with testing

- Implemented TUI auto-select for automated testing
- Fixed TUI automation: autoSelectMsg handling in Update()
- Auto-database selection in DatabaseSelector
- Created focused test suite (test_as_postgres.sh)
- Created retention policy test (test_retention.sh)
- All 10 security tests passing

Features validated:
✅ Backup retention policy (30 days, min backups)
✅ Rate limiting (exponential backoff)
✅ Privilege checks (root detection)
✅ Resource limit validation
✅ Path sanitization
✅ Checksum verification (SHA-256)
✅ Audit logging
✅ Secure permissions
✅ Configuration persistence
✅ TUI automation framework

Test results: 10/10 passed
Backup files created with .dump, .sha256, .info
Retention cleanup verified (old files removed)

run_tests_as_postgres.sh

@@ -0,0 +1,71 @@
+#!/bin/bash
+#
+# Test Runner Wrapper - Executes tests as postgres user
+# Usage: ./run_tests_as_postgres.sh [quick|comprehensive] [options]
+#
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+# Check if running as root
+if [ "$(id -u)" -ne 0 ]; then
+    echo "ERROR: This script must be run as root to switch to postgres user"
+    echo "Usage: sudo ./run_tests_as_postgres.sh [quick|comprehensive] [options]"
+    exit 1
+fi
+
+# Check if postgres user exists
+if ! id postgres &>/dev/null; then
+    echo "ERROR: postgres user does not exist"
+    echo "Please install PostgreSQL or create the postgres user"
+    exit 1
+fi
+
+# Determine which test to run
+TEST_TYPE="${1:-quick}"
+shift || true
+
+echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+echo "  Running tests as postgres user"
+echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+echo ""
+
+case "$TEST_TYPE" in
+    quick)
+        echo "Executing: quick_test.sh"
+        echo ""
+        # Give postgres user access to the directory
+        chmod -R 755 "$SCRIPT_DIR"
+        # Run as postgres user
+        su - postgres -c "cd '$SCRIPT_DIR' && bash quick_test.sh"
+        ;;
+    
+    comprehensive|comp)
+        echo "Executing: comprehensive_security_test.sh $*"
+        echo ""
+        # Give postgres user access to the directory
+        chmod -R 755 "$SCRIPT_DIR"
+        # Run as postgres user with any additional arguments
+        su - postgres -c "cd '$SCRIPT_DIR' && bash comprehensive_security_test.sh $*"
+        ;;
+    
+    *)
+        echo "ERROR: Unknown test type: $TEST_TYPE"
+        echo ""
+        echo "Usage: sudo ./run_tests_as_postgres.sh [quick|comprehensive] [options]"
+        echo ""
+        echo "Examples:"
+        echo "  sudo ./run_tests_as_postgres.sh quick"
+        echo "  sudo ./run_tests_as_postgres.sh comprehensive --quick"
+        echo "  sudo ./run_tests_as_postgres.sh comprehensive --cli-only"
+        echo "  sudo ./run_tests_as_postgres.sh comprehensive --verbose"
+        exit 1
+        ;;
+esac
+
+echo ""
+echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+echo "  Test execution complete"
+echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+echo ""