The radio's noise: the GNSS receiver costs 8 dB; a setting pauses it (#20)

Debug Builds: `lora noise test` changes one thing at a time, Sweeps the
band, and reports the floor under each condition; it runs on the device
by itself, since one condition pauses Wi-Fi (not saved, so a restart
brings it back). Result, at 125 kHz: -117 dBm with the antenna switched
off, -106 with the GNSS receiver in standby, -98 with it running. The
receiver's serial line isn't it (one sentence a second changes nothing),
and neither are the main loop, the CPU frequency, Wi-Fi, the screen or
the radio's own regulator, all within 1 dB.

Settings > "Pause GNSS for LoRa", off by default: the receiver waits in
standby while the radio listens or sweeps, except during a Track, and
has a Fix again about 7 s after. The GNSS App says it's paused.

11 dB remain between the antenna with GNSS quiet and the chip alone,
untouched by anything that can be switched from the firmware.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

src/apps/gnss_app.cpp

@@ -71,10 +71,12 @@ void GnssApp::draw(Canvas& c) {
     if (!gnss_.on()) {
         c.setFont(&fonts::bold);
         c.setTextColor(theme::kText);
-        c.drawString("GNSS is off", 4, area.y + 4);
+        bool held = gnss_.heldForLora();
+        c.drawString(held ? "GNSS is paused" : "GNSS is off", 4, area.y + 4);
         c.setFont(&fonts::body);
         c.setTextColor(theme::kMuted);
-        c.drawString("Settings > GNSS turns it on.", 4, area.y + 22);
+        c.drawString(held ? "The LoRa radio is listening, and" : "Settings > GNSS turns it on.", 4, area.y + 22);
+        if (held) c.drawString("Settings pauses GNSS for it.", 4, area.y + 22 + theme::kLineHeight);
         return;
     }
     sky_ ? drawSky(c) : drawPosition(c);