fix: remove duplicate Y-axis negation in PinLocator.get_pin_location

The symbol-to-schematic y-flip was applied twice in sequence (two identical
negation blocks with matching comments), cancelling out and leaving pin
Y-coordinates mirrored about the placement Y. For symmetric passives the
bug is invisible (pin 1 and pin 2 are electrically interchangeable); for
ICs with non-equivalent pins (power pins, opamp inputs, etc.) this causes
tools that go through PinLocator — connect_to_net, add_schematic_connection,
add_schematic_net_label with componentRef+pinNumber — to place connections
at the mirror-flipped pin. Verified against kicad-cli generate_netlist
ground truth: on a Device:R placed at (111.76, 83.82), pin 1 resolves to
y=80.01 (actual) vs y=87.63 (pre-fix).

This is a regression of PR #103, which originally fixed the y-negation;
the redundant second block was added subsequently.

Includes a regression test with both a straight Device:R and a rotated
Device:C to exercise the y-flip + rotation pipeline.

python/commands/pin_locator.py

@@ -384,9 +384,6 @@ class PinLocator:
 
             logger.debug(f"Pin {pin_number} relative position: ({pin_rel_x}, {pin_rel_y})")
 
-            # lib_symbols uses y-up; schematic uses y-down
-            pin_rel_y = -pin_rel_y
-
             # Mirror in local coords after y-negate (KiCad transform order)
             # mirror_x = flip across X axis → negate y
             # mirror_y = flip across Y axis → negate x

tests/test_pin_locator_y_flip.py

@@ -0,0 +1,112 @@
+"""
+Regression test for the symbol-to-schematic Y-axis flip in PinLocator.
+
+Before the fix, pin_locator.py's get_pin_location() negated pin_data["y"]
+twice in sequence (two identical blocks, one commented "Negate y here before
+rotation" and a second commented "lib_symbols uses y-up; schematic uses y-down"
+doing the exact same flip). The double-negation cancelled out, leaving pin
+Y-coordinates mirrored about the symbol placement Y. For symmetric passives
+(pin 1 and pin 2 electrically equivalent) the bug was invisible; for ICs with
+non-equivalent pins it caused misrouted connections.
+
+This test places a stock Device:R at a known absolute position and verifies
+that pin 1 (symbol y=+3.81) resolves to an absolute Y *above* the placement
+centre (i.e. placement_y - 3.81), matching KiCad's actual render and its
+kicad-cli net extraction. The pre-fix code put pin 1 below the centre.
+"""
+
+import shutil
+import sys
+import tempfile
+from pathlib import Path
+
+import pytest
+
+PYTHON_DIR = Path(__file__).parent.parent / "python"
+sys.path.insert(0, str(PYTHON_DIR))
+
+from commands.component_schematic import ComponentManager  # noqa: E402
+from commands.pin_locator import PinLocator  # noqa: E402
+from commands.schematic import SchematicManager  # noqa: E402
+
+
+@pytest.mark.unit
+def test_stock_resistor_pin_y_matches_render_convention():
+    """Stock Device:R pin 1 must resolve to placement_y - 3.81 (above centre)."""
+    template = (
+        Path(__file__).resolve().parent.parent
+        / "python"
+        / "templates"
+        / "template_with_symbols.kicad_sch"
+    )
+    if not template.exists():
+        pytest.skip(f"Test template not found at {template}")
+
+    with tempfile.TemporaryDirectory() as tmp:
+        sch_path = Path(tmp) / "regression.kicad_sch"
+        shutil.copy(template, sch_path)
+
+        sch = SchematicManager.load_schematic(str(sch_path))
+        ComponentManager.add_component(
+            sch,
+            {"type": "R", "reference": "R1", "value": "10k", "x": 100.0, "y": 100.0, "rotation": 0},
+            sch_path,
+        )
+        SchematicManager.save_schematic(sch, str(sch_path))
+
+        locator = PinLocator()
+        p1 = locator.get_pin_location(sch_path, "R1", "1")
+        p2 = locator.get_pin_location(sch_path, "R1", "2")
+
+        assert p1 is not None and p2 is not None, "PinLocator returned None"
+
+        # Device:R defines pin 1 at symbol (0, +3.81) and pin 2 at (0, -3.81).
+        # KiCad symbol space is +Y up; schematic space is +Y down. After the
+        # correct single negation, pin 1 lands at placement_y - 3.81 and pin 2
+        # at placement_y + 3.81.
+        assert p1[0] == pytest.approx(100.0), f"pin 1 X wrong: {p1[0]}"
+        assert p1[1] == pytest.approx(96.19), f"pin 1 Y wrong: {p1[1]} (expected 96.19)"
+        assert p2[0] == pytest.approx(100.0), f"pin 2 X wrong: {p2[0]}"
+        assert p2[1] == pytest.approx(103.81), f"pin 2 Y wrong: {p2[1]} (expected 103.81)"
+
+
+@pytest.mark.unit
+def test_rotated_capacitor_pin_x_matches_render_convention():
+    """Device:C rotated 90 CCW: pin 1 (was at +Y) should land on -X of placement."""
+    template = (
+        Path(__file__).resolve().parent.parent
+        / "python"
+        / "templates"
+        / "template_with_symbols.kicad_sch"
+    )
+    if not template.exists():
+        pytest.skip(f"Test template not found at {template}")
+
+    with tempfile.TemporaryDirectory() as tmp:
+        sch_path = Path(tmp) / "rot_regression.kicad_sch"
+        shutil.copy(template, sch_path)
+
+        sch = SchematicManager.load_schematic(str(sch_path))
+        ComponentManager.add_component(
+            sch,
+            {
+                "type": "C",
+                "reference": "C1",
+                "value": "100nF",
+                "x": 150.0,
+                "y": 100.0,
+                "rotation": 90,
+            },
+            sch_path,
+        )
+        SchematicManager.save_schematic(sch, str(sch_path))
+
+        locator = PinLocator()
+        p1 = locator.get_pin_location(sch_path, "C1", "1")
+        assert p1 is not None
+
+        # Device:C pin 1 is at symbol (0, +3.81). After y-negate → (0, -3.81).
+        # Rotated 90° CCW in screen coords: (0, -3.81) → (3.81, 0).
+        # Absolute: (150+3.81, 100+0) = (153.81, 100).
+        assert p1[0] == pytest.approx(153.81), f"rotated pin 1 X wrong: {p1[0]}"
+        assert p1[1] == pytest.approx(100.0), f"rotated pin 1 Y wrong: {p1[1]}"