Feature: Doppler handling for SX/FPGA RX-first architecture

[Luis1454]

Goal

Integrate Doppler handling consistent with the RX-first hardware model.

Context

Since RX/demod runs on SX/FPGA in nominal mode, Doppler support is split into:

• Hardware path (preferred): card applies/assists frequency tracking during reception.
• Ground path: software computes expected Doppler from telemetry and validates/annotates received frame quality.

Scope

• Define Doppler input model on ground side (velocity, relative radial component, reference carrier frequency).
• Compute expected Doppler offset and expose it to logs/metrics and optional control messages.
• In virtual mode, allow Doppler-shift simulation to validate robustness.
• For diagnostic IQ capture, support offline verification of Doppler assumptions.

Acceptance Criteria

• Doppler computation utility is unit-tested.
• Virtual simulator can produce Doppler-affected scenarios.
• Ground telemetry/observability includes expected Doppler and residual quality indicators.
• Integration tests validate behavior across nominal frame mode and diagnostic replay mode.