Prepare Plane Radar 0.1.6

[devnulluk]

What changed

• replace the ordinary-aircraft Hexpansion meter with a startup flourish and exceptional-traffic alerts
• restore the Keepdexpansion keyboard during ordinary radar use and default alert brightness to 100%
• hand the EEH Logo back to its official background controller when available, with a low-brightness teal/cyan ambient fallback otherwise
• add independent Logo brightness levels, current simulator screenshots, and updated user documentation
• package the release as version 0.1.6

Why

The previous aircraft-to-pixel mapping was technically functional but not visually useful on the physical expansions. This version gives the lights a smaller, clearer role: atmosphere at startup and unmistakable colour only when traffic is genuinely noteworthy.

Validation

• 71 host-side unit tests pass
• all release Python modules compile
• startup, idle, special-traffic, emergency and keyboard-input paths pass in the Tildagon simulator
• git diff --check passes
• release archive contains only the MicroPython application files