Design State-Machine Based Failsafe Manager

[yufurkan]

Objective

Create a modular and expandable Failsafe mechanism that handles receiver signal loss gracefully.

• Develop a FailsafeManager class utilizing a State Machine pattern.
• Implement a signal timeout detection algorithm (e.g., no IBUS frame for >500ms).
• Add FAILSAFE_LEVEL state: Force setpoints Roll=0, Pitch=0, and Throttle=idle.
• Ensure the architecture is strictly decoupled to allow easy integration of a GPS-based RTL state in the future.