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/kwp-review/SKILL.md

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+# KWP/FTDI edit checklist
+
+You are about to edit timing-sensitive K-Line communication code in one of:
+- `Infrastructure/Kwp/KwpCommon.cs`
+- `Infrastructure/Kwp/KW1281Connection.cs`
+- `Infrastructure/Kwp/FtdiInterface.cs`
+- `Services/Impl/KwpService.cs`
+
+Read the relevant file(s) first, then apply the following checks before and after your edit.
+
+---
+
+## Timing constraints
+
+**`KW1281Connection.SendPacket`** calls `Thread.Sleep(5)` after each byte written.
+This is the mandatory KWP inter-byte gap. Do not remove or reduce it.
+
+**`KwpCommon.WakeUp`** implements the 5-baud slow-init sequence.
+Any change to Sleep durations here will break ECU connection. Leave it alone unless
+you are explicitly fixing a timing bug and have the KW1281 spec in front of you.
+
+---
+
+## FtdiInterface lifetime
+
+`KwpService` constructs a `FtdiInterface` at the start of each operation and disposes it
+at the end. This is intentional — the ECU expects a fresh session per dialog.
+Do not try to hold `FtdiInterface` open across multiple `KwpService` calls.
+
+`FtdiInterface._buf` is a reused `byte[1]` field for single-byte reads/writes.
+Do not allocate a new array inside `ReadByte()` or `WriteByteRaw()`.
+
+---
+
+## Error handling invariant
+
+Every `KwpService` method that opens an `FtdiInterface` must dispose it in all code paths:
+
+```csharp
+FtdiInterface? iface = null;
+try
+{
+    iface = new FtdiInterface(port, KLineBaudRate);
+    // ... work ...
+}
+catch (Exception ex) { /* log */ }
+finally { iface?.Dispose(); }
+```
+
+If you add a new KwpService method, verify it follows this pattern.
+K-Line errors throw `InvalidOperationException` or `TimeoutException`.
+Do not catch and swallow these inside the method body — the ViewModel catch block depends on seeing them.
+
+---
+
+## Allocation patterns (known debt — do not worsen)
+
+`KW1281Connection` uses `List<byte>` for packet buffers throughout.
+If you want to reduce allocations, convert the entire packet path at once.
+Converting one method in isolation creates a mixed pattern that is harder to reason about.
+
+---
+
+## After your edit, verify:
+
+1. Search for `new FtdiInterface` — every occurrence has a matching `finally { iface?.Dispose(); }`
+2. `Thread.Sleep(5)` in `SendPacket` is still present
+3. `ProgressChanged` is still called with increasing percent values so the progress dialog updates
+4. No new `Thread.Sleep`, `Console.Write`, or `Logger.WriteLine` was added inside a per-byte loop