send_with_timeout now uses a 2s per-byte timeout with a deadline
loop instead of one long blocking read, checking a cancel event
between reads. SerialBridge.disconnect() sets the cancel event
before acquiring the lock, so a blocked firmware sweep aborts
within ~2s and releases the lock for clean port shutdown.
Adds send_with_timeout() to CarryoutG2Protocol for long-running
commands, and az_sweep_firmware() to both SerialBridge and DemoDevice.
Sweep and Sky Map modes now try the firmware path first (single
azscanwxp command, streaming results) and fall back to software
step-dwell-measure on error or when "Software mode" checkbox is
checked. Software sweep fixed to set EL once and move AZ only.
F1 Position (compass rose, motor control, sparklines),
F2 Signal (RSSI gauge with sub-char precision, DVB/ADC sparklines, LNA toggle),
F3 Scan (AZ/EL grid sweep with heatmap and CSV export),
F4 System (NVS table, A3981 diagnostics, motor dynamics),
F5 Console (raw serial terminal with prompt detection and safety gates).
Includes SerialBridge (thread-safe protocol wrapper), DemoDevice
(synthetic simulation for --demo mode), dark RF theme with rounded
borders and teal accents, and send_raw() on CarryoutG2Protocol.
