sprint-4: Project Editor + .appack compiler + IRudderActuator HAL + dual sensor config

Cherry-pick of ab28cb7 onto main (was missing from main branch history).

Python:
- arautopilot/core/sensor_config.py: RudderSensorConfig + DualRudderSensorConfig
  (AS5048A SPI / potentiometer, dual with cross-validation thresholds)
- arautopilot/core/vessel_config.py: add sensors: DualRudderSensorConfig field
- arautopilot/studio/compiler/appack.py: .appack compiler (ZIP with
  manifest.json + project.yaml + firmware_config.h + install_notes.txt)
- arautopilot/studio/editors/project_editor.py: full project config editor
  (vessel / actuator / sensors / PID, RBAC-gated fields, save/load .yaml/.json)
- arautopilot/studio/main_window.py: wire ProjectEditorWidget into Project tab
- tests: test_sensor_config.py (11 tests) + test_appack_compiler.py (10 tests)

Firmware:
- hal/rudder_actuator_iface.h: IRudderActuator abstract interface
- hal/rudder_actuator_hydraulic.h: reversible hydraulic pump (LEDC PWM)
- hal/rudder_actuator_electric.h: reversible DC motor + deadband compensation
- hal/rudder_actuator_factory.h: build-time type selection via AR_ACTUATOR_TYPE

Tests: 483 passed (was 462, +21 Sprint 4)

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

arautopilot/tests/test_sensor_config.py

@@ -0,0 +1,98 @@
+"""Tests for RudderSensorConfig and DualRudderSensorConfig — Sprint 4."""
+
+from __future__ import annotations
+
+import pytest
+from pydantic import ValidationError
+
+from arautopilot.core.sensor_config import (
+    DualRudderSensorConfig,
+    RudderSensorConfig,
+    RudderSensorType,
+)
+
+
+def _primary(
+    sensor_type: RudderSensorType = RudderSensorType.AS5048A_SPI,
+    cs: int = 10,
+    fsd: float = 35.0,
+) -> RudderSensorConfig:
+    return RudderSensorConfig(type=sensor_type, spi_cs_gpio=cs, full_scale_deg=fsd)
+
+
+def _redundant(cs: int = 11) -> RudderSensorConfig:
+    return RudderSensorConfig(
+        type=RudderSensorType.AS5048A_SPI,
+        label="Redundant – actuator arm",
+        spi_cs_gpio=cs,
+        full_scale_deg=35.0,
+    )
+
+
+class TestRudderSensorConfig:
+    def test_as5048a_defaults(self) -> None:
+        s = _primary()
+        assert s.type == RudderSensorType.AS5048A_SPI
+        assert s.spi_cs_gpio == 10
+        assert s.full_scale_deg == 35.0
+        assert s.zero_offset_deg == 0.0
+        assert s.divergence_alarm_deg == 3.0
+        assert s.divergence_failover_deg == 6.0
+
+    def test_potentiometer_type(self) -> None:
+        s = _primary(sensor_type=RudderSensorType.POTENTIOMETER)
+        assert s.type == RudderSensorType.POTENTIOMETER
+
+    def test_gpio_bounds(self) -> None:
+        with pytest.raises(ValidationError):
+            RudderSensorConfig(type=RudderSensorType.AS5048A_SPI, spi_cs_gpio=40)
+        with pytest.raises(ValidationError):
+            RudderSensorConfig(type=RudderSensorType.AS5048A_SPI, spi_cs_gpio=-1)
+
+    def test_full_scale_bounds(self) -> None:
+        with pytest.raises(ValidationError):
+            _primary(fsd=0.0)
+        with pytest.raises(ValidationError):
+            _primary(fsd=46.0)
+
+    def test_label_optional(self) -> None:
+        s = RudderSensorConfig(type=RudderSensorType.AS5048A_SPI)
+        assert s.label == ""
+
+    def test_extra_fields_forbidden(self) -> None:
+        with pytest.raises(ValidationError):
+            RudderSensorConfig(
+                type=RudderSensorType.AS5048A_SPI,
+                unknown_field="boom",  # type: ignore[call-arg]
+            )
+
+    def test_roundtrip_json(self) -> None:
+        s = _primary()
+        restored = RudderSensorConfig.model_validate_json(s.model_dump_json())
+        assert restored == s
+
+
+class TestDualRudderSensorConfig:
+    def test_single_sensor_mode(self) -> None:
+        d = DualRudderSensorConfig(primary=_primary())
+        assert d.redundant is None
+        assert not d.has_redundancy
+
+    def test_dual_sensor_mode(self) -> None:
+        d = DualRudderSensorConfig(primary=_primary(), redundant=_redundant())
+        assert d.redundant is not None
+        assert d.has_redundancy
+
+    def test_different_cs_pins(self) -> None:
+        d = DualRudderSensorConfig(primary=_primary(cs=10), redundant=_redundant(cs=11))
+        assert d.primary.spi_cs_gpio == 10
+        assert d.redundant is not None
+        assert d.redundant.spi_cs_gpio == 11
+
+    def test_roundtrip_yaml(self) -> None:
+        import yaml
+
+        d = DualRudderSensorConfig(primary=_primary(), redundant=_redundant())
+        data = yaml.safe_dump(d.model_dump(mode="json"))
+        restored = DualRudderSensorConfig.model_validate(yaml.safe_load(data))
+        assert restored == d