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>

python/commands/pin_locator.py

@@ -92,7 +92,7 @@ class PinLocator:
                 # legitimate same-length duplicates (e.g., per-unit
                 # repetitions in multi-unit symbols) retain stable ordering.
                 if pin_data["number"]:
-                    existing = pins.get(pin_data["number"])
+                    existing = pins.get(str(pin_data["number"]))
                     if existing is None or pin_data["length"] > existing["length"]:
                         pins[pin_data["number"]] = pin_data