Atlas cards now use the Signal tab StatCard tiles, shared Card, badges,
action buttons, IATA chips and search bar. Polling moves to TanStack Query
with the app retry policy, pauses while rate-limited, and recovers a pin
whose server ID changed by its full public key. Search results show a key
prefix and explain short or non-hex input; heard-by states which packet it
counts. Sparkline component removed in favour of the stats one.
* docs: move deployment to beacon-docs and add SHOULDERS
* docs: keep only web-specific contributor notes
* docs: show the dev proxy settings needed for live updates
MrAlders0n