Fix linting and type errors for CI

- Use X | None syntax instead of Optional[X] (UP045)
- Sort imports in dashboard app (I001)
- Remove unnecessary UTF-8 encoding argument (UP012)
- Add 'from err' to exception re-raises (B904)
- Remove unused imports in integration tests (F401)
- Fix useless expression in test (B018)
- Cast **1.5 result to float in LDO model (mypy no-any-return)
- Use functools.partial instead of lambda in server (mypy misc)

src/py_dvt_ate/simulation/physics/models/ldo.py

@@ -194,7 +194,7 @@ class LDOModel:
         # Temperature ratio (reference is approximately 300K ≈ 27°C)
         temp_ratio = t_kelvin / 300.0
 
-        return self._params.dropout_voltage * (temp_ratio**1.5)
+        return float(self._params.dropout_voltage * (temp_ratio**1.5))
 
     def is_in_dropout(self, junction_temperature: float) -> bool:
         """Check if the LDO is in dropout at current operating point.

src/py_dvt_ate/simulation/virtual/chamber.py

@@ -82,8 +82,8 @@ class ThermalChamberSim(BaseInstrument):
 
         try:
             setpoint = float(command.arguments[0])
-        except ValueError:
-            raise ValueError(f"Invalid temperature value: {command.arguments[0]}")
+        except ValueError as err:
+            raise ValueError(f"Invalid temperature value: {command.arguments[0]}") from err
 
         self._setpoint = setpoint
         if self._physics_engine is not None:

src/py_dvt_ate/simulation/virtual/power_supply.py

@@ -94,8 +94,8 @@ class PowerSupplySim(BaseInstrument):
 
         try:
             voltage = float(command.arguments[0])
-        except ValueError:
-            raise ValueError(f"Invalid voltage value: {command.arguments[0]}")
+        except ValueError as err:
+            raise ValueError(f"Invalid voltage value: {command.arguments[0]}") from err
 
         if voltage < 0:
             raise ValueError("Voltage cannot be negative")
@@ -127,8 +127,8 @@ class PowerSupplySim(BaseInstrument):
 
         try:
             current = float(command.arguments[0])
-        except ValueError:
-            raise ValueError(f"Invalid current value: {command.arguments[0]}")
+        except ValueError as err:
+            raise ValueError(f"Invalid current value: {command.arguments[0]}") from err
 
         if current < 0:
             raise ValueError("Current limit cannot be negative")