feat: add mil unit support across position/coordinate commands (#162)

* feat(units): add mil unit support across all position/coordinate commands

KiCad natively supports mils, so the MCP server should too. Added "mil"
as a valid unit option in tool schemas and updated all unit-to-nanometer
scale conversions across component, routing, outline, view, and IPC
handler code paths. 1 mil = 25400 nm (0.0254 mm).

Also fixes a pre-existing mypy overload error in pin_locator.py (str cast
on dict.get key) that was blocking pre-commit on any Python file change.

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

* feat(units): add mil to TypeScript tool schemas

The Python-side mil support was added but the actual input validation
happens in the TypeScript/Zod schemas. Updated all z.enum(["mm", "inch"])
to include "mil" across board, component, routing, design-rules, and
export tool definitions.

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

* fix(tools): replace CP-1252 mojibake with correct Unicode in board.ts

Replace U+00C3 U+00D7 (×) with U+00D7 (×) in add_logo size output string.
Character was mangled when file was saved as CP-1252 instead of UTF-8.

* fix: restore em-dash and fix pre-commit mypy in component/routing

component.py: replace CP-1252 mojibake (â€") with correct Unicode
em-dash (—) in the 'Add to board first' comment. Addresses
maintainer review on PR #162.

routing.py: annotate ex/ey as float at first assignment site in
_point_to_segment_distance_nm so mypy pre-commit hook passes
cleanly on this branch.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_mil_unit_support.py

@@ -0,0 +1,106 @@
+"""Tests for ``mil`` unit support across position/coordinate commands.
+
+KiCad natively understands mils (1 mil = 0.0254 mm = 25 400 nm). The MCP
+server now accepts ``"mil"`` as a value of the ``unit`` field everywhere a
+position or coordinate is specified. Tests below assert:
+
+  - The ``unit→nanometer`` scale used in command handlers maps mil → 25 400.
+  - The IPC handler converts mil positions to mm before calling the IPC API.
+  - The Python tool schema enums include ``"mil"`` (it was previously
+    restricted to ``["mm", "inch"]``).
+"""
+
+import sys
+from pathlib import Path
+from typing import Any
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "python"))
+
+# Scale used by the per-command handlers when they convert position values
+# to KiCad internal nanometers.
+MIL_TO_NM = 25_400
+MM_TO_NM = 1_000_000
+INCH_TO_NM = 25_400_000
+
+
+def _scale(unit: str) -> int:
+    """Mirror of the inline ternary used in commands/* for position scaling."""
+    return 1_000_000 if unit == "mm" else (25_400 if unit == "mil" else 25_400_000)
+
+
+def test_scale_mapping_includes_mil():
+    assert _scale("mm") == MM_TO_NM
+    assert _scale("mil") == MIL_TO_NM
+    assert _scale("inch") == INCH_TO_NM
+
+
+def test_one_thousand_mil_equals_one_inch_in_nm():
+    """Sanity check: 1000 mil should produce the same nm offset as 1 inch."""
+    one_inch = 1 * _scale("inch")
+    one_thousand_mil = 1000 * _scale("mil")
+    assert one_inch == one_thousand_mil
+
+
+def _make_iface() -> Any:
+    with patch("kicad_interface.USE_IPC_BACKEND", True):
+        from kicad_interface import KiCADInterface
+
+        iface = KiCADInterface.__new__(KiCADInterface)
+    iface.use_ipc = True
+    iface.board = None
+    iface.ipc_board_api = MagicMock()
+    iface.ipc_board_api.place_component.return_value = True
+    iface.ipc_board_api.move_component.return_value = True
+    return iface
+
+
+def test_ipc_place_component_converts_mil_to_mm():
+    iface = _make_iface()
+    iface._ipc_place_component(
+        {
+            "reference": "R1",
+            "footprint": "Resistor_SMD:R_0805",
+            "position": {"x": 100, "y": 200, "unit": "mil"},
+            "rotation": 0,
+            "layer": "F.Cu",
+            "value": "220",
+        }
+    )
+    _, kwargs = iface.ipc_board_api.place_component.call_args
+    assert kwargs["x"] == pytest.approx(2.54)
+    assert kwargs["y"] == pytest.approx(5.08)
+
+
+def test_ipc_move_component_converts_mil_to_mm():
+    iface = _make_iface()
+    iface._ipc_move_component({"reference": "R1", "position": {"x": 1000, "y": 500, "unit": "mil"}})
+    _, kwargs = iface.ipc_board_api.move_component.call_args
+    assert kwargs["x"] == pytest.approx(25.4)
+    assert kwargs["y"] == pytest.approx(12.7)
+
+
+def test_python_tool_schema_unit_enums_include_mil():
+    """Every unit enum in TOOL_SCHEMAS must include mil."""
+    from schemas.tool_schemas import TOOL_SCHEMAS
+
+    def _find_unit_enums(node):
+        """Walk the schema and yield every enum list found under 'unit' fields."""
+        if isinstance(node, dict):
+            for k, v in node.items():
+                if k == "unit" and isinstance(v, dict) and "enum" in v:
+                    yield v["enum"]
+                else:
+                    yield from _find_unit_enums(v)
+        elif isinstance(node, list):
+            for item in node:
+                yield from _find_unit_enums(item)
+
+    enums = list(_find_unit_enums(TOOL_SCHEMAS))
+    assert enums, "Expected at least one unit enum in TOOL_SCHEMAS"
+    for enum in enums:
+        assert "mil" in enum, f"Unit enum {enum} is missing 'mil'"
+        # Sanity: mm and inch should still be present too
+        assert "mm" in enum and "inch" in enum, f"Unit enum {enum} is malformed"