Improve Maldet installation error handling and diagnostics

Problem:
- Maldet installation was failing silently on Plesk servers
- No error output to diagnose issues (./install.sh &>/dev/null)
- Users only saw "✗ Maldet installation failed" with no context

Changes:
- Add comprehensive error capture to /tmp/maldet-install-$$.log
- Show last 10 lines of installation output on failure
- Add step-by-step progress indicators (download, extract, install)
- Check each operation and fail fast with clear error messages
- Add Plesk-specific diagnostics:
  • Detect Plesk installation
  • Check cron directory permissions
  • Verify /usr/local/sbin exists
- Preserve full log file for detailed investigation
- Return proper exit codes for error handling

This enables users to diagnose and fix Plesk-specific installation
issues instead of being stuck with a generic failure message.

modules/security/malware-scanner.sh

@@ -218,19 +218,48 @@ install_all_scanners() {
     if ! is_maldet_installed; then
         echo -e "${CYAN}[2/4] Installing Maldet...${NC}"
 
-        cd /tmp
-        wget -q http://www.rfxn.com/downloads/maldetect-current.tar.gz
+        cd /tmp || { echo -e "${RED}✗ Cannot access /tmp${NC}"; return 1; }
 
-        if [ -f maldetect-current.tar.gz ]; then
-            tar -xzf maldetect-current.tar.gz
-            cd maldetect-* 2>/dev/null
-            ./install.sh &>/dev/null
-            cd /tmp
-            rm -rf "maldetect-"*
+        # Download Maldet
+        echo "  → Downloading Maldet..."
+        if ! wget -q http://www.rfxn.com/downloads/maldetect-current.tar.gz; then
+            echo -e "${RED}✗ Download failed - check internet connectivity${NC}"
+            return 1
         fi
 
+        if [ -f maldetect-current.tar.gz ]; then
+            echo "  → Extracting archive..."
+            if ! tar -xzf maldetect-current.tar.gz 2>/dev/null; then
+                echo -e "${RED}✗ Extraction failed - archive may be corrupted${NC}"
+                rm -f maldetect-current.tar.gz
+                return 1
+            fi
+
+            # Change to extracted directory
+            if ! cd maldetect-* 2>/dev/null; then
+                echo -e "${RED}✗ Cannot find extracted directory${NC}"
+                cd /tmp
+                rm -rf "maldetect-"*
+                return 1
+            fi
+
+            # Run installation with error capture
+            echo "  → Running installation script..."
+            local install_log="/tmp/maldet-install-$$.log"
+            if ./install.sh > "$install_log" 2>&1; then
+                install_exit=0
+            else
+                install_exit=$?
+            fi
+
+            # Cleanup
+            cd /tmp
+            rm -rf "maldetect-"*
+
+            # Check if installation succeeded
             if is_maldet_installed; then
                 echo -e "${GREEN}✓ Maldet installed${NC}"
+                rm -f "$install_log"
 
                 # Update malware signatures immediately
                 echo "  → Updating malware signatures..."
@@ -238,6 +267,35 @@ install_all_scanners() {
                 echo -e "  ${GREEN}✓${NC} Signatures updated"
             else
                 echo -e "${RED}✗ Maldet installation failed${NC}"
+
+                # Show diagnostic information
+                if [ -f "$install_log" ]; then
+                    echo -e "${YELLOW}Installation output (last 10 lines):${NC}"
+                    tail -10 "$install_log" | sed 's/^/  /'
+                    echo ""
+                    echo -e "${YELLOW}Full log saved to: $install_log${NC}"
+                fi
+
+                # Check for common Plesk issues
+                if command -v plesk >/dev/null 2>&1; then
+                    echo -e "${YELLOW}Detected Plesk system - checking for conflicts...${NC}"
+
+                    # Check if cron is accessible
+                    if [ ! -w /var/spool/cron ] && [ ! -w /etc/cron.d ]; then
+                        echo "  → Cron directory permissions may be restricted"
+                    fi
+
+                    # Check if required directories exist
+                    if [ ! -d /usr/local/sbin ]; then
+                        echo "  → /usr/local/sbin does not exist (required for maldet)"
+                    fi
+                fi
+
+                return 1
+            fi
+        else
+            echo -e "${RED}✗ Download failed - maldetect-current.tar.gz not found${NC}"
+            return 1
         fi
     else
         echo -e "${GREEN}✓ Maldet already installed${NC}"