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/test_ipc_backend.py

@@ -16,6 +16,7 @@ Usage:
 
 import os
 import sys
+from typing import Any, Optional
 
 # Add parent directory to path
 sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
@@ -29,7 +30,7 @@ logging.basicConfig(
 logger = logging.getLogger(__name__)
 
 
-def test_connection():
+def test_connection() -> Optional[Any]:
     """Test basic IPC connection to KiCAD."""
     print("\n" + "=" * 60)
     print("TEST 1: IPC Connection")
@@ -62,7 +63,7 @@ def test_connection():
         return None
 
 
-def test_board_access(backend):
+def test_board_access(backend: Any) -> Optional[Any]:
     """Test board access and component listing."""
     print("\n" + "=" * 60)
     print("TEST 2: Board Access")
@@ -93,7 +94,7 @@ def test_board_access(backend):
         return None
 
 
-def test_board_info(board_api):
+def test_board_info(board_api: Any) -> bool:
     """Test getting board information."""
     print("\n" + "=" * 60)
     print("TEST 3: Board Information")
@@ -134,7 +135,7 @@ def test_board_info(board_api):
         return False
 
 
-def test_realtime_track(board_api, interactive=False):
+def test_realtime_track(board_api: Any, interactive: bool = False) -> bool:
     """Test adding a track in real-time (appears immediately in KiCAD UI)."""
     print("\n" + "=" * 60)
     print("TEST 4: Real-time Track Addition")
@@ -168,7 +169,7 @@ def test_realtime_track(board_api, interactive=False):
         return False
 
 
-def test_realtime_via(board_api, interactive=False):
+def test_realtime_via(board_api: Any, interactive: bool = False) -> bool:
     """Test adding a via in real-time (appears immediately in KiCAD UI)."""
     print("\n" + "=" * 60)
     print("TEST 5: Real-time Via Addition")
@@ -200,7 +201,7 @@ def test_realtime_via(board_api, interactive=False):
         return False
 
 
-def test_realtime_text(board_api, interactive=False):
+def test_realtime_text(board_api: Any, interactive: bool = False) -> bool:
     """Test adding text in real-time."""
     print("\n" + "=" * 60)
     print("TEST 6: Real-time Text Addition")
@@ -229,7 +230,7 @@ def test_realtime_text(board_api, interactive=False):
         return False
 
 
-def test_selection(board_api, interactive=False):
+def test_selection(board_api: Any, interactive: bool = False) -> bool:
     """Test getting the current selection from KiCAD UI."""
     print("\n" + "=" * 60)
     print("TEST 7: UI Selection")
@@ -255,7 +256,7 @@ def test_selection(board_api, interactive=False):
         return False
 
 
-def run_all_tests(interactive=False):
+def run_all_tests(interactive: bool = False) -> bool:
     """Run all IPC backend tests."""
     print("\n" + "=" * 60)
     print("KiCAD IPC Backend Test Suite")