ci: mypy ratchet -- keep type-clean modules clean (71 modules, 536 -> 442 errors) (#661)

* ci: mypy ratchet -- keep type-clean modules clean

mypy-clean.txt lists the 71 modules under src/ that type-check clean;
scripts/check_types.py runs mypy (--follow-imports=silent) on exactly
those files and fails on any error or a missing/unsorted/duplicate entry.
A new "Type check (mypy ratchet)" CI job runs it with mypy 1.20.2 and
pinned stubs; the manual pre-commit mypy hook now runs the same script
(a local hook, so mypy sees the installed requirements like CI does).

35 modules were made clean with annotation-only fixes: hints, typing.cast,
TYPE_CHECKING imports, implicit-Optional defaults made explicit, and
annotations widened (never guards removed) where mypy called a defensive
isinstance check unreachable. No runtime behaviour change.

mypy.ini: numpy and orjson are treated as Any (follow_imports=skip, also
for stubs). numpy 2.3+ stubs use 3.12 `type` statements that mypy won't
parse at python_version 3.10, and orjson is optional, so seeing its stubs
made the result depend on whether it was installed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* chore: annotate check_types.py's list-form mypy subprocess

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

src/plugin_system/testing/loading.py

@@ -7,7 +7,7 @@ plugin discovery / manifest / config-default logic lives in exactly one place.
 
 import json
 from pathlib import Path
-from typing import Any, Dict, Optional, Sequence, Union
+from typing import Any, Dict, Optional, Sequence, Union, cast
 
 
 def find_plugin_dir(plugin_id: str, search_dirs: Sequence[Union[str, Path]]) -> Optional[Path]:
@@ -39,7 +39,7 @@ def load_manifest(plugin_dir: Union[str, Path]) -> Dict[str, Any]:
     if not manifest_path.exists():
         raise FileNotFoundError(f"No manifest.json in {plugin_dir}")
     with open(manifest_path, 'r', encoding='utf-8') as f:
-        return json.load(f)
+        return cast(Dict[str, Any], json.load(f))
 
 
 def merge_config(base: Dict[str, Any], override: Dict[str, Any]) -> Dict[str, Any]:
@@ -64,7 +64,7 @@ def load_schema(plugin_dir: Union[str, Path]) -> Optional[Dict[str, Any]]:
     if not schema_path.exists():
         return None
     with open(schema_path, 'r', encoding='utf-8') as f:
-        return json.load(f)
+        return cast(Optional[Dict[str, Any]], json.load(f))
 
 
 def load_config_defaults(plugin_dir: Union[str, Path]) -> Dict[str, Any]:
@@ -124,7 +124,7 @@ def load_harness_spec(plugin_dir: Union[str, Path]) -> Dict[str, Any]:
     if not spec_path.exists():
         return {}
     with open(spec_path, 'r', encoding='utf-8') as f:
-        spec = json.load(f)
+        spec: Dict[str, Any] = json.load(f)
 
     # Resolve mock_data path and inline its contents for convenience.
     mock_rel = spec.get('mock_data')

src/plugin_system/testing/mocks.py

@@ -6,7 +6,7 @@ and plugin_manager for use in plugin unit tests.
 """
 
 import warnings
-from typing import Dict, Any, Optional
+from typing import Dict, Any, List, Optional
 from PIL import Image
 
 #: Why draw_image() warns. Kept (rather than removed) so existing plugin test
@@ -32,7 +32,7 @@ class MockDisplayManager:
         self.image = Image.new('RGB', (width, height), color=(0, 0, 0))
         self.clear_called = False
         self.update_called = False
-        self.draw_calls = []
+        self.draw_calls: List[Dict[str, Any]] = []
     
     def clear(self):
         """Clear the display."""
@@ -43,7 +43,7 @@ class MockDisplayManager:
         """Update the display."""
         self.update_called = True
     
-    def draw_text(self, text: str, x: int = None, y: int = None, color: tuple = (255, 255, 255),
+    def draw_text(self, text: str, x: Optional[int] = None, y: Optional[int] = None, color: tuple = (255, 255, 255),
                   font=None, small_font: bool = False, centered: bool = False):
         """Draw text on the display.
 
@@ -166,8 +166,8 @@ class MockConfigManager:
     
     def __init__(self, config: Optional[Dict[str, Any]] = None):
         self._config = config or {}
-        self.load_config_calls = []
-        self.save_config_calls = []
+        self.load_config_calls: List[Dict[str, Any]] = []
+        self.save_config_calls: List[Dict[str, Any]] = []
     
     def load_config(self) -> Dict[str, Any]:
         """Load configuration."""