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/wire_dragger.py

@@ -7,7 +7,7 @@ All methods operate on in-memory sexpdata lists (no disk I/O).
 import logging
 import math
 import uuid
-from typing import Dict, List, Optional, Tuple
+from typing import Any, Dict, List, Optional, Tuple
 
 import sexpdata
 from sexpdata import Symbol
@@ -55,7 +55,7 @@ class WireDragger:
     """Pure-logic helpers for wire-endpoint dragging during component moves."""
 
     @staticmethod
-    def find_symbol(sch_data: list, reference: str):
+    def find_symbol(sch_data: list, reference: str) -> Any:
         """
         Find a placed symbol by reference designator.
 
@@ -218,7 +218,7 @@ class WireDragger:
         junction_k = _K["junction"]
         at_k = _K["at"]
 
-        def find_new(x: float, y: float):
+        def find_new(x: float, y: float) -> Optional[Tuple[float, float]]:
             for (ox, oy), (nx, ny) in old_to_new.items():
                 if _coords_match(x, y, ox, oy, eps):
                     return nx, ny