chore: enable strict mypy checks and fix pre-commit mypy hook

Add type annotations to all previously untyped functions and remove 9
suppressed error codes (call-arg, assignment, return-value, operator,
has-type, dict-item, misc, list-item, annotation-unchecked) by fixing
the underlying type issues.

Add [[tool.mypy.overrides]] with ignore_missing_imports for KiCAD-specific
modules (pcbnew, sexpdata, skip, cairosvg, kipy, PIL) so the pre-commit
mypy hook passes in its isolated venv. Add types-requests and pytest to
additional_dependencies in .pre-commit-config.yaml.

Also fixes several real bugs uncovered by stricter checks: incorrect static
calls to instance methods in swig_backend, wrong return type on get_size,
missing value param in BoardAPI.place_component, variable shadowing in
kicad_process.py, unqualified LibraryManager reference in kicad_interface,
and missing top-level Path import.

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

python/commands/footprint.py

@@ -238,7 +238,10 @@ class FootprintCreator:
                     changes.append(f"drill (inserted)→{new_drill}")
             if shape:
                 block, n = re.subn(
-                    r'(pad\s+"[^"]*"\s+\w+\s+)\w+', lambda m: m.group(1) + shape, block, count=1
+                    r'(pad\s+"[^"]*"\s+\w+\s+)\w+',
+                    lambda m: str(m.group(1)) + shape,
+                    block,
+                    count=1,
                 )
                 if n:
                     changes.append(f"shape→{shape}")