#184: Strip non-printable chars (<0x20 except tab/newline) from ADVERT
names in Go server decoder, Go ingestor decoder, and Node decoder.js.
#185: Add visual (N) badge next to node names when multiple nodes share
the same display name (case-insensitive). Shows in list, side pane, and
full detail page with 'also known as' links to other keys.
#186: Add packetsLast24h field to /api/stats response.
#187#188: Cache runtime.ReadMemStats() with 5s TTL in Go server.
#189: Temporarily patch HTMLCanvasElement.prototype.getContext during
L.heatLayer().addTo(map) to pass { willReadFrequently: true }, preventing
Chrome console warning about canvas readback performance.
Tests: 10 new tests for buildDupNameMap + dupNameBadge (143 total frontend).
Cache busters bumped.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>