Fix store_reference errors in malware scanner

- Added missing source for reference-db.sh library in malware-scanner.sh:15
- Created store_reference() and get_reference() functions in reference-db.sh
- Functions use REF|key|value format in .sysref database
- Fixes "store_reference: command not found" errors at lines 816-817

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

modules/security/malware-scanner.sh

@@ -12,6 +12,7 @@ SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
 source "$SCRIPT_DIR/lib/common-functions.sh" 2>/dev/null || true
 source "$SCRIPT_DIR/lib/system-detect.sh" 2>/dev/null || true
 source "$SCRIPT_DIR/lib/user-manager.sh" 2>/dev/null || true
+source "$SCRIPT_DIR/lib/reference-db.sh" 2>/dev/null || true
 
 # Arrays for docroots and scanners
 declare -a docroot_array