v0.2.1

Much lighter on the badge

The app was redrawing the whole screen ~15 times a second for a display whose data changes once every 15 seconds. It now redraws only when what would appear on screen actually differs from what is already there, with a slow one-per-second tick to keep the "updated N seconds ago" counter honest, and full-rate drawing only while something genuinely animates — a menu, a notification, the sweep, armed-alert pulsing, or a finger on the touch ring.

Measured in the simulator:

	draws/sec	ctx calls/sec
Before	15.3	4,660
After	1.0	271

The saving grows with traffic: 30 contacts on an 80 km scope over Heathrow is about 1,300 ctx calls a second, against roughly 11,000 before.

Also:

• The LED ring is only written when the frame actually changes, and the OS pattern generator is told to stay off once a second rather than five times.
• New "Max contacts" setting (10 / 20 / 30 / 50). Each contact costs an aircraft outline and a label-placement attempt on every redraw, so it is the biggest lever you have. It was in the config file but not the menu.
• The README now documents the measurements and which settings cost the most, in order of effect.
• No log spam on a 2024 badge, which has no touch ring.

No change to what the app shows or how it is used.