semantics: complete DEF-to-region migration, fix regressions

- Convert legacy [DEF🆔Type] anchors to #region/#endregion across 329 files
- Reinstate _normalize_timestamp_value in sql_generator.py
- Fix MarkerLogger→logger migration in events.py (molecular CoT markers)
- Fix dataset_review orchestrator dependencies (_build_execution_snapshot)
- Fix config_manager stale-record deletion (moved to save path only)
- Add 77 missing [/DEF:] closers in 5 unbalanced test files
- Update assistant_chat.integration.test.js for #region format
- Apply molecular-cot-logging markers (REASON/REFLECT/EXPLORE) via logger.* methods

backend/src/plugins/llm_analysis/__init__.py

@@ -1,4 +1,4 @@
-# #region backend/src/plugins/llm_analysis/__init__.py [TYPE Module]
+# [DEF:backend/src/plugins/llm_analysis/__init__.py:Module]
 
 """
 LLM Analysis Plugin for automated dashboard validation and dataset documentation.
@@ -8,4 +8,4 @@ from .plugin import DashboardValidationPlugin, DocumentationPlugin
 
 __all__ = ['DashboardValidationPlugin', 'DocumentationPlugin']
 
-# #endregion backend/src/plugins/llm_analysis/__init__.py
+# [/DEF:backend/src/plugins/llm_analysis/__init__.py:Module]