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/18_VoicePrank.txt

@@ -0,0 +1,10 @@
+REM ========================================
+REM NullSec Flipper Zero BadUSB
+REM Payload: Text-to-Speech Prank
+REM Target: Windows 10/11
+REM ========================================
+DELAY 1000
+GUI r
+DELAY 500
+STRING powershell -w hidden -c "Add-Type -AssemblyName System.Speech;$s=New-Object System.Speech.Synthesis.SpeechSynthesizer;$s.Speak('I am watching you. I can see everything you do. Your computer now belongs to NullSec.')"
+ENTER