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>

.claude/skills/build/SKILL.md

@@ -0,0 +1,20 @@
+# Build HC_APTBS
+
+Build the WPF application targeting Windows x64.
+
+## Steps
+
+1. Run the build from the solution root:
+
+```bash
+dotnet build -r win-x64 "C:/Users/herli/Documents/ClaudeProjects/HC_APTBS/HC_APTBS.slnx"
+```
+
+2. Parse the output:
+   - If the build **succeeds**: report the number of warnings (if any) and confirm success.
+   - If the build **fails**: list each error with file path and line number, then suggest fixes.
+
+## Notes
+- Always use `-r win-x64` — native DLLs (`PCANBasic.dll`, `ftd2xx.dll`) are x64 Windows binaries.
+- SDK version is pinned in `global.json`. Do not modify it.
+- There is no test project. Build success is the only automated check.