Add flight route lookup, helicopter marker, and QR code for WebUI

Detail panel now shows origin/destination via adsbdb.com callsign
lookup. Rotorcraft (ADS-B category A7) get a distinct rotor-cross
marker instead of a heading arrowhead, same rationale as the existing
ground-vehicle marker. WebUI info screen gets a QR button (when WiFi
is connected) that renders the local WebUI URL as a scannable code.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/i18n_en.h

@@ -239,6 +239,8 @@ static const char* const I18N_EN[] = {
     "Deleting all data...",
     "Reset failed.",
     "Tap to skip",
+    "Route: ",
+    "Scan with your phone:",
 };
 
 static_assert(sizeof(I18N_EN) / sizeof(I18N_EN[0]) == (size_t)StringId::COUNT,