fix: say which devices a recording is captured from

A station with two radios has two sets of audio endpoints, and the recorder will
happily capture the one nobody is listening to — a Flex DAX channel while the
operator works a Yaesu over USB. The file is then full of hiss with no relation
to what they hear, unaffected by the rig's AGC, and nothing anywhere said which
receiver it came from.

The device names are now logged, resolved to their friendly names, once when
capture starts.

internal/audio/recorder.go

@@ -204,6 +204,18 @@ func (r *Recorder) Start(fromDev, micDev string, prerollSec int) error {
 		}()
 	}
 
+	// Name the devices being recorded FROM, once, at the start.
+	//
+	// A station with two radios has two sets of endpoints, and the recorder will
+	// happily capture the one that is not being listened to: the result is a
+	// file full of hiss with no relation to what the operator hears, and nothing
+	// anywhere said which receiver it came from.
+	if twoSrc {
+		LogSink("recorder: capturing %q + %q", DeviceName(fromDev), DeviceName(micDev))
+	} else {
+		LogSink("recorder: capturing %q", DeviceName(fromDev))
+	}
+
 	// Watchdog. A WASAPI device can open cleanly and then produce nothing at
 	// all — a DAX channel with no stream behind it does exactly that, and it is
 	// indistinguishable from silence until the recording turns out to be empty