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>

log_pruner.py

@@ -10,7 +10,7 @@ class LogPruner:
     are preserved long-term.
     """
 
- def __init__(self, log_registry: LogRegistry, logs_dir: str):
+ def __init__(self, log_registry: LogRegistry, logs_dir: str) -> None:
   """
         Initializes the LogPruner.
 
@@ -21,7 +21,7 @@ class LogPruner:
   self.log_registry = log_registry
   self.logs_dir = logs_dir
 
- def prune(self):
+ def prune(self) -> None:
   """
         Prunes old and small session directories from the logs directory.