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/schematic_analysis.py

@@ -782,7 +782,7 @@ def find_wires_crossing_symbols(schematic_path: Path) -> List[Dict[str, Any]]:
     collisions = []
 
     # Pre-compute per-symbol data
-    symbol_data = []
+    symbol_data: List[Dict[str, Any]] = []
     for sym in symbols:
         ref = sym["reference"]
         if sym["is_power"] or ref.startswith("_TEMPLATE") or not ref: