iNAV RealFlight bridge — fly on a real tune

This update adds a new, much lower-latency way to connect SITL Forge to **iNAV SITL**, plus real-time physics improvements that benefit every flight mode.

## ✨ New: iNAV RealFlight transport (recommended)

SITL Forge now speaks iNAV's native **RealFlight** interface (`--sim=rf`). Instead of streaming sensors over MSP and polling for motor outputs, iNAV runs **in lockstep** with the simulator — it advances one step per exchange and pushes its motors to us directly.

What that means for you: **heavy quads finally fly on a normal PID tune.** The old MSP path forced a near-zero I-term or the craft would oscillate; the RealFlight bridge removes that latency, so your 10" / 13" builds hold attitude the way they should.

• Lockstep, low-latency control loop - iNAV pushes motors directly — no polling round-trip - GPS / nav modes (POSHOLD, RTH, waypoints) driven by your simulated position - Now the **default** transport — MSP HITL remains available as a fallback

Setup takes a few extra launch flags on iNAV's side — the in-app **Help** panel on the iNAV card walks you through both modes step by step.

## ⚙️ Real-time physics fix (all modes)

Physics now holds a true real-time 1000 Hz even when the frame rate dips, instead of slipping into slow motion. This tightens the control loop for **Betaflight, iNAV, and the built-in SIM controller** alike.

## 🛠️Other improvements

• **iNAV MSP mode:** smoother attitude feed to the flight controller — less frozen-pose wobble even on the legacy transport. - **Tuning window:** the "applied" message now matches the tab you're on (Vibration, Sensors, Camera…) instead of always reading "PID/Rates sent to firmware." - **Docs:** the iNAV setup guide has been rewritten to cover both transports, GPS setup, and troubleshooting.

Happy flying — feedback welcome!