fix(core): move RedactingFormatter import before conditional block

RedactingFormatter was imported inside 'if not has_errors_log_handler:'
(line 461) but also used unconditionally in the verbose_logging block
(line 479). When the error log handler already exists (e.g. second
AIAgent in the same process) AND verbose_logging=True, the import was
skipped and line 479 raised NameError.

Fix: Move the import one level up so it's always available regardless
of whether the error log handler already exists.

run_agent.py

@@ -457,8 +457,8 @@ class AIAgent:
             and Path(getattr(handler, "baseFilename", "")).resolve() == resolved_error_log_path
             for handler in root_logger.handlers
         )
+        from agent.redact import RedactingFormatter
         if not has_errors_log_handler:
-            from agent.redact import RedactingFormatter
             error_log_dir.mkdir(parents=True, exist_ok=True)
             error_file_handler = RotatingFileHandler(
                 error_log_path, maxBytes=2 * 1024 * 1024, backupCount=2,