Release v0.9.75 runtime and onboarding update

Ship the 0.9.75 source update with improved startup/runtime hardening, operator API key onboarding, Meshtastic MQTT controls, Infonet/MeshChat separation, desktop package versioning, and aircraft telemetry refinements.

Also updates focused backend/frontend tests for node settings, Meshtastic MQTT settings, and desktop runtime behavior.

backend/Dockerfile

@@ -22,10 +22,12 @@ FROM python:3.11-slim-bookworm
 
 WORKDIR /app
 
-# Install Node.js (for AIS WebSocket proxy) and curl (for network fallback)
+# Install Node.js (for AIS WebSocket proxy), curl (for network fallback), and
+# Tor (for Wormhole/remote-agent .onion transport).
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \
     curl \
+    tor \
     && curl -fsSL https://deb.nodesource.com/setup_20.x | bash - \
     && apt-get install -y --no-install-recommends nodejs \
     && rm -rf /var/lib/apt/lists/*