Add NullSec BadUSB payload collection

Added 25 BadUSB payloads for Flipper Zero:
- System reconnaissance (Windows/Linux/Mac)
- Credential extraction & WiFi password stealing
- Reverse shells (PowerShell & Bash)
- Defense evasion & persistence
- Data exfiltration (keylogger, webcam, clipboard)
- Harmless pranks

All payloads include proper headers and documentation.
Cross-platform support for Windows, Linux, and macOS.

BadUSB/NullSec-BadUSB/20_InvertScreen.txt

@@ -0,0 +1,10 @@
+REM ========================================
+REM NullSec Flipper Zero BadUSB
+REM Payload: Invert Screen Colors
+REM Target: Windows 10/11
+REM ========================================
+DELAY 1000
+GUI r
+DELAY 500
+STRING powershell -c "Set-ItemProperty 'HKCU:\Software\Microsoft\ColorFiltering' -Name Active -Value 1 -Type DWord -Force; Set-ItemProperty 'HKCU:\Software\Microsoft\ColorFiltering' -Name FilterType -Value 1 -Type DWord -Force"
+ENTER