Version 2.2.0 - Unified calibration + native pulsing support

v2.2: Unified calibration + native pulsing + auto-calibration

• Added native pulsing support with hardware PWM (compile-time configurable)
• Added automatic calibration with 90-day database caching
• Updated Arduino firmware to light_controller_v2_2_arduino/
• Added protocol visualization tools (preview_protocol.py, viz_protocol_html.py)