feat: redesign bench calibration (factor/offset), add Ttank/P2 displays, fix sensor calibration

- Replace P1-P6 rational transfer function with factor/offset model for bench params
- Add explicit rx/tx direction flags in bench XML configuration
- Add T.Tank (BenchTemp) and P2 (AnalogSensor2) to temperature/pressure display
- Apply SensorConfiguration calibration to pressure channels, fix empty sensors.xml fallback
- Add live value labels to flowmeter charts
- Hide pump live values and PSG encoder standalone label
- Add K-Line connection state model, improve KWP service and status displays
- Restructure .claude/skills into subdirectory format

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ViewModels/DfiManageViewModel.cs

@@ -31,6 +31,10 @@ namespace HC_APTBS.ViewModels
         {
             _kwp    = kwpService;
             _config = configService;
+
+            // Update the slider and LCD display in real time when the DFI is
+            // read during a full K-Line read (PumpIdentificationViewModel flow).
+            _kwp.DfiRead += (dfi) => SetDfi(dfi);
         }
 
         // ── DFI display ───────────────────────────────────────────────────────────