The EGSM900 band table had start=925e6 but ARFCNs 0-124 use downlink
frequencies starting at 935 MHz (DL = 935 + 0.2*ARFCN). The 925 MHz
value is the E-GSM extension band (ARFCNs 975-1023).
This caused grgsm_livemon to tune 10 MHz too low — ARFCN 22 tuned to
929.4 MHz instead of 939.4 MHz, receiving no GSM frames and producing
zero GSMTAP packets for tshark to capture.
Also adds EGSM900_EXT band (ARFCNs 975-1023, DL 925.2-934.8 MHz)
and diagnostic logging in the monitor thread to track raw tshark
line counts vs parsed packets.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
c6a8a4a492