refactor(types): auto -> None sweep across entire codebase

Applied 236 return type annotations to functions with no return values
across 100+ files (core modules, tests, scripts, simulations).
Added Phase 4 to python_style_refactor track for remaining 597 items
(untyped params, vars, and functions with return values).

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

theme.py

@@ -1,4 +1,4 @@
-# theme.py
+# theme.py
 """
 Theming support for manual_slop GUI.
 
@@ -289,7 +289,7 @@ def get_palette_colours(name: str) -> dict:
  """Return a copy of the colour dict for the named palette."""
  return dict(_PALETTES.get(name, {}))
 
-def apply(palette_name: str, overrides: dict | None = None):
+def apply(palette_name: str, overrides: dict | None = None) -> None:
  """
     Build a global DPG theme from the named palette plus optional per-colour
     overrides, and bind it as the default theme.
@@ -332,7 +332,7 @@ def apply(palette_name: str, overrides: dict | None = None):
  dpg.bind_theme(t)
  _current_theme_tag = t
 
-def apply_font(font_path: str, size: float = 14.0):
+def apply_font(font_path: str, size: float = 14.0) -> None:
  """
     Load the TTF at font_path at the given point size and bind it globally.
     Safe to call multiple times.  Uses a single persistent font_registry; only
@@ -362,13 +362,13 @@ def apply_font(font_path: str, size: float = 14.0):
  _current_font_tag = font
  dpg.bind_font(font)
 
-def set_scale(factor: float):
+def set_scale(factor: float) -> None:
  """Set the global Dear PyGui font/UI scale factor."""
  global _current_scale
  _current_scale = factor
  dpg.set_global_font_scale(factor)
 
-def save_to_config(config: dict):
+def save_to_config(config: dict) -> None:
  """Persist theme settings into the config dict under [theme]."""
  config.setdefault("theme", {})
  config["theme"]["palette"]   = _current_palette
@@ -376,7 +376,7 @@ def save_to_config(config: dict):
  config["theme"]["font_size"] = _current_font_size
  config["theme"]["scale"]     = _current_scale
 
-def load_from_config(config: dict):
+def load_from_config(config: dict) -> None:
  """Read [theme] from config and apply everything."""
  t = config.get("theme", {})
  palette   = t.get("palette",   "DPG Default")