Add Windows support with BladeRF A4

[Skeletoskull]

Major changes:

• Add BladeRF A4 SDR support using GNU Radio osmosdr
• Implement Windows-compatible path handling (path_utils.py)
• Add frequency scanner with intelligent locking mechanism
• Optimize signal processing (faster STFT, early exit, reduced I/O)
• Add JSON output format with timestamps and telemetry
• Add comprehensive system documentation (SYSTEM_OVERVIEW.md)
• Update README with Windows setup instructions
• Add performance optimizations for real-time processing
• Add test suite with pytest and hypothesis

Hardware tested:

• BladeRF A4, BladeRF 2.0 micro xA4
• Windows 10/11, Ubuntu 20.04+
• DJI Mini 2, Mavic Air 2, Mavic 2 (legacy mode)

Performance improvements:

• 33% faster frequency scanning (1.4s vs 2.1s per frequency)
• Early exit after finding packets
• Optional file saving for maximum speed
• Optimized STFT parameters (noverlap=0, smaller nfft)

Maintains backward compatibility with original Linux/USRP implementation."